AFP012000

General Information

Protein Name Antifreeze protein
Gene Name in Uniprot AFP type II
UniProt ID Q91992
Nucleotide Sequence ID in NCBI L14722 / S65819.1
Protein Sequence ID in NCBI AAA49200.1 / AAB28093.1
Species Clupea harengus (Atlantic herring)
Sequence Length 130
Sequence
Structure PDB ID: 2py2
Solvent Accessible Surface Area Total SASA 21217.21 Ų Polar SASA 13432.20 Ų Apolar SASA 34649.42 Ų

AFP012000000

Mutation Wild Type
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP WT-6H
Tag Hexahistidine
Ice crystal morphology Fig.4.A Ice crystal morphology of hAFP and its CaCR mutants. The samples were (A) buffer alone and wild-type hAFP WT-6H. The protein concentrations used for each sample are indicated.
Ice crystal morphology
PMID 9521729
DOI 10.1021/bi972503w
Protein Name hAFP(herring AFP)
Tag Hexahistidine
Ice crystal morphology Fig.4.B Ice crystal morphologies in the AFP solutions used to measure thermal hysteresis. Protein concentrations are 0.10, 0.5, 0.75, and 1.5 mg/mL in panels 1-4, respectively. A protein-free control is also shown. The magnification used was 400X.
Ice crystal morphology
PMID 8663288
DOI 10.1074/jbc.271.28.16627
Protein Name hAFP
Ice crystal morphology Fig.6 Antifreeze activity of hAFP in the presence of metals. Ice crystals were grown in solutions of 4 mg/ml AFP. Crystals are shown with the a and c axes indicated. An exception is the crystal grown in the absence of added ion that has the a axis parallel to the page and the c axis normal to the page. Added metal ions are indicated. Crystals were videotaped at temperatures below the melting point. Individual frames were then transferred into image files.
Ice crystal morphology
PMID 16887111
DOI 10.1016/j.cryobiol.2006.06.006
Protein Name Recombinant type II AFP (herring)
Tag Hexahistidine
Ice crystal morphology Fig.2.(3) Ice crystal bursts in the presence of moderately active Wsh AFPs. Images of ice crystals seen in frames A-D were taken at 0.4 s intervals during the burst. Sequences 1-6 were obtained with type I AFP from winter Xounder plasma, shorthorn sculpin plasma, recombinant type II AFP (herring), recombinant type II (sea raven), recombinant type III AFP and low molecular weight AFGPs from Gadus ogac, respectively. The AFP concentrations and thermal hysteresis activities for each AFP are given in Table 1. Each AFP was assayed in 100 mM ammonium bicarbonate (pH 7.9). The herring type II AFP sample also contained 10 mM CaCl2. The direction of the c-axis is shown in frame A by the white arrow.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP WT-6H
Tag Hexahistidine
Thermal Hysteresis Fig.3 Thermal hysteresis activity of hAFP and its CaCR mutants Q92A, D94A, N113A, and N113D. (A) Measurements of concentration-dependent thermal hysteresis of wild-type hAFP WT6H and its mutants. (B) Relative thermal hysteresis of hAFP CaCR mutants (0.4 mM) compared with that of WT-6H.
Thermal Hysteresis
PMID 9521729
DOI 10.1021/bi972503w
Protein Name hAFP(herring AFP)
Tag Hexahistidine
Thermal Hysteresis Fig.4.A Antifreeze activity (thermal hysteresis) of solutions containing a series of AFP concentrations was measured as described under Experimental Procedures using a Clifton nanoliter osmometer. Values shown represent means ±SD of triplicate measurements done on single samples. The curve was fitted using the data pooled from the native and recombinant AFPs.
Thermal Hysteresis
PMID 8663288
DOI 10.1074/jbc.271.28.16627
Protein Name hAFP
Thermal Hysteresis Fig.5 Antifreeze activity of hAFP as a function of added metals. A, antifreeze activity of solutions containing 4 mg/ml AFP and a series of CaCl2 concentrations was measured. Antifreeze activity of AFP was also measured in the absence of metal ions and in the presence of 10 mM metal ions.(B) and 3 mM ruthenium red as described under “Experimental Procedures” (C). For B and C, the average activity in the presence of Ca21 was normalized to 100%. Each bar represents the mean 6 S.E. of three preparations.
Thermal Hysteresis
PMID 16887111
DOI 10.1016/j.cryobiol.2006.06.006
Protein Name Recombinant type II AFP (herring)
Tag Hexahistidine
Thermal Hysteresis Tab.1 Recombinant type II (herring).
Thermal Hysteresis
PMID 11281719
DOI 10.1006/prep.2001.1395
Protein Name Native
Thermal Hysteresis Fig.7 Antifreeze activities of WT and WT-6H. Concentration-dependent antifreeze activities were measured as described under Materials and Methods using a Clifton nanoliter osmometer. Valuesshown represent means of triplicate measure ments done on eachsingle sample.
Thermal Hysteresis
PMID 11281719
DOI 10.1006/prep.2001.1395
Protein Name hAFP WT-6H
Thermal Hysteresis Fig.7 Antifreeze activities of WT and WT-6H. Concentration-dependent antifreeze activities were measured as described under Materials and Methods using a Clifton nanoliter osmometer. Valuesshown represent means of triplicate measure ments done on eachsingle sample.
Thermal Hysteresis
PMID 11281719
DOI 10.1006/prep.2001.1395
Protein Name hAFP WT
Tag Hexahistidine
Thermal Hysteresis Fig.7 Antifreeze activities of WT and WT-6H. Concentration-dependent antifreeze activities were measured as described under Materials and Methods using a Clifton nanoliter osmometer. Valuesshown represent means of triplicate measure ments done on eachsingle sample.
Ice Binding Sites
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP WT-6H
Tag Hexahistidine
IBS The ice-binding site(IBS) is located at the Ca2²⁺-binding site (CaBS), and the loop region defined by residues E99 and D114 is crucial for ice binding.
Ice Binding Sites
PMID 9521729
DOI 10.1021/bi972503w
Protein Name hAFP(herring AFP)
Tag Hexahistidine
IBS The ice-binding site is located at the Ca²⁺-binding site, which corresponds to the carbohydrate-binding site of C-type lectins.
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.
PMID: 9521729
DOI: 10.1021/bi972503w
1. The refolded rAFP binds Ca²⁺ and exhibits a Ca²⁺-dependent protease resistance as the native AFP does.
2. The ice-binding site of the Atlantic herring type II antifreeze protein corresponds to the carbohydrate-binding site of C-type lectins.
3. The ice-binding function of the antifreeze protein may have evolved from the carbohydrate-binding site of a pre-existing C-type lectin.
PMID: 8663288
DOI: 10.1074/jbc.271.28.16627
1. The results show that hAFP requires a single Ca²⁺ binding site, where key residues E99 and D114 are essential for both calcium coordination and ice binding, enabling thermal hysteresis (TH) activity.
2. In the absence of Ca²⁺ hAFP loses its antifreeze function, highlighting the crucial role of metal ion binding in maintaining its structural stability and activity.
PMID: 16887111
DOI: 10.1016/j.cryobiol.2006.06.006
1. The study reveals that hyperactive AFPs are significantly more effective at depressing the freezing point of solutions than moderately active fish AFPs.
2. The key distinction lies in their ability to prevent ice growth out of the basal planes, resulting in ice crystals that burst explosively perpendicular to the c-axis when cooled below the freezing temperature.
3. This mechanism is proposed to be the foundation for the hyperactivity of these proteins.
PMID: 11281719
DOI: 10.1006/prep.2001.1395
1. Recombinant herring antifreeze protein was successfully expressed in Pichia pastoris and exhibited antifreeze activity comparable to the native protein.
2. The C-terminal histidine tag has a minimal effect on the antifreeze activity of herring antifreeze protein.
3. The antifreeze activity and conformation of antifreeze proteins are Ca²⁺-dependent, and recombinant antifreeze proteins also have Ca²⁺-binding ability.

AFP012000001

Mutation Q92E,D94N
Sequence
Ice crystal morphology
PMID 9521729
DOI 10.1021/bi972503w
Protein Name hAFP(EPN,mutant)
Tag Hexahistidine
Ice crystal morphology Fig.4.B Ice crystal morphologies in the AFP solutions used to measure thermal hysteresis. Protein concentrations are 0.10, 0.5, 0.75, and 1.5 mg/mL in panels 1-4, respectively. A protein-free control is also shown. The magnification used was 400X.
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(EPN)
Tag Hexahistidine
Ice crystal morphology Fig.4.C Ice crystal morphology of hAFP and its CaCR mutants. The samples were (C) hAFP mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 9521729
DOI 10.1021/bi972503w
Protein Name hAFP(EPN,mutant)
Tag Hexahistidine
Thermal Hysteresis Fig.4.A Antifreeze activity (thermal hysteresis) of solutions containing a series of AFP concentrations was measured as described under Experimental Procedures using a Clifton nanoliter osmometer. Values shown represent means ±SD of triplicate measurements done on single samples. The curve was fitted using the data pooled from the native and recombinant AFPs.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(EPN)
Tag Hexahistidine
Thermal Hysteresis "It is noted that mutant EPN showed only a trace of thermal hysteresis, even at 0.96 mM protein concentration."
Brief description
PMID: 9521729
DOI: 10.1021/bi972503w
1. The ice-binding site of the Atlantic herring type II antifreeze protein corresponds to the carbohydrate-binding site of C-type lectins.
2. The mutant antifreeze protein can bind Ca²⁺ normally and fold correctly, but it loses its antifreeze activity.
3. The ice-binding function of the antifreeze protein may have evolved from the carbohydrate-binding site of a pre-existing C-type lectin.
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000002

Mutation Q92A
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(Q92A)
Tag Hexahistidine
Ice crystal morphology Fig.4.B Ice crystal morphology of hAFP and its CaCR mutants. The samples were (B) hAFP mutants with reduced thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(Q92A)
Tag Hexahistidine
Thermal Hysteresis Fig.3 Thermal hysteresis activity of hAFP and its CaCR mutants Q92A, D94A, N113A, and N113D. (A) Measurements of concentration-dependent thermal hysteresis of wild-type hAFP WT6H and its mutants. (B) Relative thermal hysteresis of hAFP CaCR mutants (0.4 mM) compared with that of WT-6H.
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000003

Mutation D94A
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(D94A)
Tag Hexahistidine
Ice crystal morphology Fig.4.B Ice crystal morphology of hAFP and its CaCR mutants. The samples were (B) hAFP mutants with reduced thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(D94A)
Tag Hexahistidine
Thermal Hysteresis Fig.3 Thermal hysteresis activity of hAFP and its CaCR mutants Q92A, D94A, N113A, and N113D. (A) Measurements of concentration-dependent thermal hysteresis of wild-type hAFP WT6H and its mutants. (B) Relative thermal hysteresis of hAFP CaCR mutants (0.4 mM) compared with that of WT-6H.
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000004

Mutation N113A
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(N113A)
Tag Hexahistidine
Ice crystal morphology Fig.4.B Ice crystal morphology of hAFP and its CaCR mutants. The samples were (B) hAFP mutants with reduced thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(N113A)
Tag Hexahistidine
Thermal Hysteresis Fig.3 Thermal hysteresis activity of hAFP and its CaCR mutants Q92A, D94A, N113A, and N113D. (A) Measurements of concentration-dependent thermal hysteresis of wild-type hAFP WT6H and its mutants. (B) Relative thermal hysteresis of hAFP CaCR mutants (0.4 mM) compared with that of WT-6H.
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000005

Mutation N113D
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(N113D)
Tag Hexahistidine
Ice crystal morphology Fig.4.B Ice crystal morphology of hAFP and its CaCR mutants. The samples were (B) hAFP mutants with reduced thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(N113D)
Tag Hexahistidine
Thermal Hysteresis Fig.3 Thermal hysteresis activity of hAFP and its CaCR mutants Q92A, D94A, N113A, and N113D. (A) Measurements of concentration-dependent thermal hysteresis of wild-type hAFP WT6H and its mutants. (B) Relative thermal hysteresis of hAFP CaCR mutants (0.4 mM) compared with that of WT-6H.
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000006

Mutation Q92E
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(Q92E)
Tag Hexahistidine
Ice crystal morphology Fig.4.C Ice crystal morphology of hAFP and its CaCR mutants. The samples were (C) hAFP mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(Q92E)
Tag Hexahistidine
Thermal Hysteresis "... which retained the ability to modify the ice crystal with no detectable thermal hysteresis."
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000007

Mutation Q92T
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(Q92T)
Tag Hexahistidine
Ice crystal morphology Fig.4.C Ice crystal morphology of hAFP and its CaCR mutants. The samples were (C) hAFP mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(Q92T)
Tag Hexahistidine
Thermal Hysteresis "... which retained the ability to modify the ice crystal with no detectable thermal hysteresis."
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000008

Mutation D94N
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(D94N)
Tag Hexahistidine
Ice crystal morphology Fig.4.C Ice crystal morphology of hAFP and its CaCR mutants. The samples were (C) hAFP mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(D94N)
Tag Hexahistidine
Thermal Hysteresis "... which retained the ability to modify the ice crystal with no detectable thermal hysteresis."
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000009

Mutation E99A
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(E99A)
Tag Hexahistidine
Ice crystal morphology Fig.4.C Ice crystal morphology of hAFP and its CaCR mutants. The samples were (C) hAFP mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(E99A)
Tag Hexahistidine
Thermal Hysteresis E99A only modified the ice crystal with no detectable thermal hysteresis activity.
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000010

Mutation E99D
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(E99D)
Tag Hexahistidine
Ice crystal morphology Fig.4.C Ice crystal morphology of hAFP and its CaCR mutants. The samples were (C) hAFP mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(E99D)
Tag Hexahistidine
Thermal Hysteresis "... which retained the ability to modify the ice crystal with no detectable thermal hysteresis."
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000011

Mutation E99Q
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(E99Q)
Tag Hexahistidine
Ice crystal morphology Fig.4.C Ice crystal morphology of hAFP and its CaCR mutants. The samples were (C) hAFP mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(E99Q)
Tag Hexahistidine
Thermal Hysteresis "... which retained the ability to modify the ice crystal with no detectable thermal hysteresis."
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000012

Mutation E99Q,N113D
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(E99Q/N113D)
Tag Hexahistidine
Ice crystal morphology Fig.4.C Ice crystal morphology of hAFP and its CaCR mutants. The samples were (C) hAFP mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(E99Q/N113D)
Tag Hexahistidine
Thermal Hysteresis Activity measurement for the double mutant E99Q/ N113D showed normal ​Calcium ion binding affinity with no detectable thermal hysteresis.
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000013

Mutation Q92K
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(Q92K)
Tag Hexahistidine
Ice crystal morphology Fig.4.D Ice crystal morphology of hAFP and its CaCR mutants. The samples were (D) hAFP mutants that completely lost thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(Q92K)
Tag Hexahistidine
Thermal Hysteresis "The nonactive mutant Q92K … abolished the antifreeze activity completely."
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000014

Mutation D94E
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(D94E)
Tag Hexahistidine
Ice crystal morphology Fig.4.D Ice crystal morphology of hAFP and its CaCR mutants. The samples were (D) hAFP mutants that completely lost thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(D94E)
Tag Hexahistidine
Thermal Hysteresis "mutants with longer side chains, such as Q92K and D94E, … abolished the antifreeze activity completely."
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000015

Mutation D94T
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(D94T)
Tag Hexahistidine
Ice crystal morphology Fig.4.D Ice crystal morphology of hAFP and its CaCR mutants. The samples were (D) hAFP mutants that completely lost thermal hysteresis. The protein concentrations used for each sample are indicated.
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000016

Mutation E99H
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(E99H)
Tag Hexahistidine
Ice crystal morphology Fig.4.D Ice crystal morphology of hAFP and its CaCR mutants. The samples were (D) hAFP mutants that completely lost thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(E99H)
Tag Hexahistidine
Thermal Hysteresis "E99H, which contained a bulky residue that might cause steric hindrance, completely lost its activity."
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000017

Mutation D114A
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(D114A)
Tag Hexahistidine
Ice crystal morphology Fig.4.D Ice crystal morphology of hAFP and its CaCR mutants. The samples were (D) hAFP mutants that completely lost thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(D114A)
Tag Hexahistidine
Thermal Hysteresis D114A was devoid of any thermal hysteresis.
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000018

Mutation D114E
Sequence
Ice crystal morphology
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(D114E)
Tag Hexahistidine
Ice crystal morphology Fig.4.D Ice crystal morphology of hAFP and its CaCR mutants. The samples were (D) hAFP mutants that completely lost thermal hysteresis. The protein concentrations used for each sample are indicated.
Thermal Hysteresis
PMID 15544325
DOI 10.1021/bi048485h
Protein Name hAFP(D114E)
Tag Hexahistidine
Thermal Hysteresis "Isoelectric alternates D94E, E99D, and D114E did not show higher antifreeze activity…"
Brief description
PMID: 15544325
DOI: 10.1021/bi048485h
1. The ice-binding site of herring type II antifreeze protein hAFP is located at the Ca²⁺-binding site.
2. Residues E99 and D114 are essential for the activity of hAFP to inhibit ice crystal growth.
3. Different mutations have different effects on the thermal hysteresis activity of hAFP. The thermal hysteresis activity of some mutants is significantly reduced or even disappears.

AFP012000019

Mutation A90H
Sequence
Ice crystal morphology
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (A90H)
Tag Hexahistidine
Ice crystal morphology Fig.7.B.(3) Ice crystal morphologies of hAFP and its mutants. Samples were: (1) buffer alone and wild-type hAFP; (2) the mutant that exhibited no effect on thermal hysteresis; (3) mutants that showed reduced thermal hysteresis activities; (4) mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis activities, (5) mutants that exhibited complete loss of antifreeze activity. The protein concentration used for each sample is also indicated.
Thermal Hysteresis
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (A90H)
Tag Hexahistidine
Thermal Hysteresis Fig.7.A.1 (A) Concentration dependent thermal hysteresis activity of (1) WT-6H (●), mutants Ala90Ser (□), Ala90His (◼), Ala91His (▲), and Ala91Thr (△), and (2) WT-6H (●), mutants Thr95Ala (▲), Thr95Ile (△), Gln103Ala (□), Gly109Asp (○), and His121Ala (◼), was measured as described under "Materials and Methods" using a Clifton nanoliter osmometer. Values showed represent means of triplicate measurements done on each single sample.
Brief description
PMID: 17579720
DOI: 10.1371/journal.pone.0000548
1. Determined the 1.7 Å crystal structure of herring type II AFP(hAFP), which resembles the C-type lectins and has unique ice-binding features.
2. Identified the ice-binding site of hAFP consisting of Thr96, Thr98, and Ca²⁺ coordinating residues Asp94 and Glu99, and the Ca²⁺ ion strengthens the interaction with ice.
3. Phylogenetic analysis showed that all type II AFPs evolved from a common ancestor and developed different ice-binding modes, originating from an ancestral duplication of a gene encoding a mannose or galactose-binding lectin.

AFP012000020

Mutation A90S
Sequence
Ice crystal morphology
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (A90S)
Tag Hexahistidine
Ice crystal morphology Fig.7.B.(3) Ice crystal morphologies of hAFP and its mutants. Samples were: (1) buffer alone and wild-type hAFP; (2) the mutant that exhibited no effect on thermal hysteresis; (3) mutants that showed reduced thermal hysteresis activities; (4) mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis activities, (5) mutants that exhibited complete loss of antifreeze activity. The protein concentration used for each sample is also indicated.
Thermal Hysteresis
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (A90S)
Tag Hexahistidine
Thermal Hysteresis Fig.7.A.1 (A) Concentration dependent thermal hysteresis activity of (1) WT-6H (●), mutants Ala90Ser (□), Ala90His (◼), Ala91His (▲), and Ala91Thr (△), and (2) WT-6H (●), mutants Thr95Ala (▲), Thr95Ile (△), Gln103Ala (□), Gly109Asp (○), and His121Ala (◼), was measured as described under "Materials and Methods" using a Clifton nanoliter osmometer. Values showed represent means of triplicate measurements done on each single sample.
Brief description
PMID: 17579720
DOI: 10.1371/journal.pone.0000548
1. Determined the 1.7 Å crystal structure of herring type II AFP(hAFP), which resembles the C-type lectins and has unique ice-binding features.
2. Identified the ice-binding site of hAFP consisting of Thr96, Thr98, and Ca²⁺ coordinating residues Asp94 and Glu99, and the Ca²⁺ ion strengthens the interaction with ice.
3. Phylogenetic analysis showed that all type II AFPs evolved from a common ancestor and developed different ice-binding modes, originating from an ancestral duplication of a gene encoding a mannose or galactose-binding lectin.

AFP012000021

Mutation A91H
Sequence
Ice crystal morphology
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (A91H)
Tag Hexahistidine
Ice crystal morphology Fig.7.B.(3) Ice crystal morphologies of hAFP and its mutants. Samples were: (1) buffer alone and wild-type hAFP; (2) the mutant that exhibited no effect on thermal hysteresis; (3) mutants that showed reduced thermal hysteresis activities; (4) mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis activities, (5) mutants that exhibited complete loss of antifreeze activity. The protein concentration used for each sample is also indicated.
Thermal Hysteresis
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (A91H)
Tag Hexahistidine
Thermal Hysteresis Fig.7.A.1 (A) Concentration dependent thermal hysteresis activity of (1) WT-6H (●), mutants Ala90Ser (□), Ala90His (◼), Ala91His (▲), and Ala91Thr (△), and (2) WT-6H (●), mutants Thr95Ala (▲), Thr95Ile (△), Gln103Ala (□), Gly109Asp (○), and His121Ala (◼), was measured as described under "Materials and Methods" using a Clifton nanoliter osmometer. Values showed represent means of triplicate measurements done on each single sample.
Brief description
PMID: 17579720
DOI: 10.1371/journal.pone.0000548
1. Determined the 1.7 Å crystal structure of herring type II AFP(hAFP), which resembles the C-type lectins and has unique ice-binding features.
2. Identified the ice-binding site of hAFP consisting of Thr96, Thr98, and Ca²⁺ coordinating residues Asp94 and Glu99, and the Ca²⁺ ion strengthens the interaction with ice.
3. Phylogenetic analysis showed that all type II AFPs evolved from a common ancestor and developed different ice-binding modes, originating from an ancestral duplication of a gene encoding a mannose or galactose-binding lectin.

AFP012000022

Mutation A91T
Sequence
Ice crystal morphology
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (A91T)
Tag Hexahistidine
Ice crystal morphology Fig.7.B.(3) Ice crystal morphologies of hAFP and its mutants. Samples were: (1) buffer alone and wild-type hAFP; (2) the mutant that exhibited no effect on thermal hysteresis; (3) mutants that showed reduced thermal hysteresis activities; (4) mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis activities, (5) mutants that exhibited complete loss of antifreeze activity. The protein concentration used for each sample is also indicated.
Thermal Hysteresis
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (A91T)
Tag Hexahistidine
Thermal Hysteresis Fig.7.A.1 (A) Concentration dependent thermal hysteresis activity of (1) WT-6H (●), mutants Ala90Ser (□), Ala90His (◼), Ala91His (▲), and Ala91Thr (△), and (2) WT-6H (●), mutants Thr95Ala (▲), Thr95Ile (△), Gln103Ala (□), Gly109Asp (○), and His121Ala (◼), was measured as described under "Materials and Methods" using a Clifton nanoliter osmometer. Values showed represent means of triplicate measurements done on each single sample.
Brief description
PMID: 17579720
DOI: 10.1371/journal.pone.0000548
1. Determined the 1.7 Å crystal structure of herring type II AFP(hAFP), which resembles the C-type lectins and has unique ice-binding features.
2. Identified the ice-binding site of hAFP consisting of Thr96, Thr98, and Ca²⁺ coordinating residues Asp94 and Glu99, and the Ca²⁺ ion strengthens the interaction with ice.
3. Phylogenetic analysis showed that all type II AFPs evolved from a common ancestor and developed different ice-binding modes, originating from an ancestral duplication of a gene encoding a mannose or galactose-binding lectin.

AFP012000023

Mutation T95A
Sequence
Ice crystal morphology
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (T95A)
Tag Hexahistidine
Ice crystal morphology Fig.7.B.(3) Ice crystal morphologies of hAFP and its mutants. Samples were: (1) buffer alone and wild-type hAFP; (2) the mutant that exhibited no effect on thermal hysteresis; (3) mutants that showed reduced thermal hysteresis activities; (4) mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis activities, (5) mutants that exhibited complete loss of antifreeze activity. The protein concentration used for each sample is also indicated.
Thermal Hysteresis
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (T95A)
Tag Hexahistidine
Thermal Hysteresis Fig.7.A.2 T95A (A) Concentration dependent thermal hysteresis activity of (1) WT-6H (●), mutants Ala90Ser (□), Ala90His (◼), Ala91His (▲), and Ala91Thr (△), and (2) WT-6H (●), mutants Thr95Ala (▲), Thr95Ile (△), Gln103Ala (□), Gly109Asp (○), and His121Ala (◼), was measured as described under "Materials and Methods" using a Clifton nanoliter osmometer. Values showed represent means of triplicate measurements done on each single sample.
Brief description
PMID: 17579720
DOI: 10.1371/journal.pone.0000548
1. Determined the 1.7 Å crystal structure of herring type II AFP(hAFP), which resembles the C-type lectins and has unique ice-binding features.
2. Identified the ice-binding site of hAFP consisting of Thr96, Thr98, and Ca²⁺ coordinating residues Asp94 and Glu99, and the Ca²⁺ ion strengthens the interaction with ice.
3. Phylogenetic analysis showed that all type II AFPs evolved from a common ancestor and developed different ice-binding modes, originating from an ancestral duplication of a gene encoding a mannose or galactose-binding lectin.

AFP012000024

Mutation T95I
Sequence
Ice crystal morphology
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (T95I)
Tag Hexahistidine
Ice crystal morphology Fig.7.B.(3) Ice crystal morphologies of hAFP and its mutants. Samples were: (1) buffer alone and wild-type hAFP; (2) the mutant that exhibited no effect on thermal hysteresis; (3) mutants that showed reduced thermal hysteresis activities; (4) mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis activities, (5) mutants that exhibited complete loss of antifreeze activity. The protein concentration used for each sample is also indicated.
Thermal Hysteresis
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (T95I)
Tag Hexahistidine
Thermal Hysteresis Fig.7.A.2 T95A (A) Concentration dependent thermal hysteresis activity of (1) WT-6H (●), mutants Ala90Ser (□), Ala90His (◼), Ala91His (▲), and Ala91Thr (△), and (2) WT-6H (●), mutants Thr95Ala (▲), Thr95Ile (△), Gln103Ala (□), Gly109Asp (○), and His121Ala (◼), was measured as described under "Materials and Methods" using a Clifton nanoliter osmometer. Values showed represent means of triplicate measurements done on each single sample.
Brief description
PMID: 17579720
DOI: 10.1371/journal.pone.0000548
1. Determined the 1.7 Å crystal structure of herring type II AFP(hAFP), which resembles the C-type lectins and has unique ice-binding features.
2. Identified the ice-binding site of hAFP consisting of Thr96, Thr98, and Ca²⁺ coordinating residues Asp94 and Glu99, and the Ca²⁺ ion strengthens the interaction with ice.
3. Phylogenetic analysis showed that all type II AFPs evolved from a common ancestor and developed different ice-binding modes, originating from an ancestral duplication of a gene encoding a mannose or galactose-binding lectin.

AFP012000025

Mutation G109D
Sequence
Ice crystal morphology
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (G109D)
Tag Hexahistidine
Ice crystal morphology Fig.7.B.(2) Ice crystal morphologies of hAFP and its mutants. Samples were: (1) buffer alone and wild-type hAFP; (2) the mutant that exhibited no effect on thermal hysteresis; (3) mutants that showed reduced thermal hysteresis activities; (4) mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis activities, (5) mutants that exhibited complete loss of antifreeze activity. The protein concentration used for each sample is also indicated.
Thermal Hysteresis
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (G109D)
Tag Hexahistidine
Thermal Hysteresis Fig.7.A.2 T95A (A) Concentration dependent thermal hysteresis activity of (1) WT-6H (●), mutants Ala90Ser (□), Ala90His (◼), Ala91His (▲), and Ala91Thr (△), and (2) WT-6H (●), mutants Thr95Ala (▲), Thr95Ile (△), Gln103Ala (□), Gly109Asp (○), and His121Ala (◼), was measured as described under "Materials and Methods" using a Clifton nanoliter osmometer. Values showed represent means of triplicate measurements done on each single sample.
Brief description
PMID: 17579720
DOI: 10.1371/journal.pone.0000548
1. Determined the 1.7 Å crystal structure of herring type II AFP(hAFP), which resembles the C-type lectins and has unique ice-binding features.
2. Identified the ice-binding site of hAFP consisting of Thr96, Thr98, and Ca²⁺ coordinating residues Asp94 and Glu99, and the Ca²⁺ ion strengthens the interaction with ice.
3. Phylogenetic analysis showed that all type II AFPs evolved from a common ancestor and developed different ice-binding modes, originating from an ancestral duplication of a gene encoding a mannose or galactose-binding lectin.

AFP012000026

Mutation Q103A
Sequence
Ice crystal morphology
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (Q103A)
Tag Hexahistidine
Ice crystal morphology Fig.7.B.(3) Ice crystal morphologies of hAFP and its mutants. Samples were: (1) buffer alone and wild-type hAFP; (2) the mutant that exhibited no effect on thermal hysteresis; (3) mutants that showed reduced thermal hysteresis activities; (4) mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis activities, (5) mutants that exhibited complete loss of antifreeze activity. The protein concentration used for each sample is also indicated.
Thermal Hysteresis
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (Q103A)
Tag Hexahistidine
Thermal Hysteresis Fig.7.A.2 T95A (A) Concentration dependent thermal hysteresis activity of (1) WT-6H (●), mutants Ala90Ser (□), Ala90His (◼), Ala91His (▲), and Ala91Thr (△), and (2) WT-6H (●), mutants Thr95Ala (▲), Thr95Ile (△), Gln103Ala (□), Gly109Asp (○), and His121Ala (◼), was measured as described under "Materials and Methods" using a Clifton nanoliter osmometer. Values showed represent means of triplicate measurements done on each single sample.
Brief description
PMID: 17579720
DOI: 10.1371/journal.pone.0000548
1. Determined the 1.7 Å crystal structure of herring type II AFP(hAFP), which resembles the C-type lectins and has unique ice-binding features.
2. Identified the ice-binding site of hAFP consisting of Thr96, Thr98, and Ca²⁺ coordinating residues Asp94 and Glu99, and the Ca²⁺ ion strengthens the interaction with ice.
3. Phylogenetic analysis showed that all type II AFPs evolved from a common ancestor and developed different ice-binding modes, originating from an ancestral duplication of a gene encoding a mannose or galactose-binding lectin.

AFP012000027

Mutation H121A
Sequence
Ice crystal morphology
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (H121A)
Tag Hexahistidine
Ice crystal morphology Fig.7.B.(3) Ice crystal morphologies of hAFP and its mutants. Samples were: (1) buffer alone and wild-type hAFP; (2) the mutant that exhibited no effect on thermal hysteresis; (3) mutants that showed reduced thermal hysteresis activities; (4) mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis activities, (5) mutants that exhibited complete loss of antifreeze activity. The protein concentration used for each sample is also indicated.
Thermal Hysteresis
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (H121A)
Tag Hexahistidine
Thermal Hysteresis Fig.7.A.2 T95A (A) Concentration dependent thermal hysteresis activity of (1) WT-6H (●), mutants Ala90Ser (□), Ala90His (◼), Ala91His (▲), and Ala91Thr (△), and (2) WT-6H (●), mutants Thr95Ala (▲), Thr95Ile (△), Gln103Ala (□), Gly109Asp (○), and His121Ala (◼), was measured as described under "Materials and Methods" using a Clifton nanoliter osmometer. Values showed represent means of triplicate measurements done on each single sample.
Brief description
PMID: 17579720
DOI: 10.1371/journal.pone.0000548
1. Determined the 1.7 Å crystal structure of herring type II AFP(hAFP), which resembles the C-type lectins and has unique ice-binding features.
2. Identified the ice-binding site of hAFP consisting of Thr96, Thr98, and Ca²⁺ coordinating residues Asp94 and Glu99, and the Ca²⁺ ion strengthens the interaction with ice.
3. Phylogenetic analysis showed that all type II AFPs evolved from a common ancestor and developed different ice-binding modes, originating from an ancestral duplication of a gene encoding a mannose or galactose-binding lectin.

AFP012000028

Mutation T96I
Sequence
Ice crystal morphology
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (T96I)
Tag Hexahistidine
Ice crystal morphology Fig.7.B.(5) Ice crystal morphologies of hAFP and its mutants. Samples were: (1) buffer alone and wild-type hAFP; (2) the mutant that exhibited no effect on thermal hysteresis; (3) mutants that showed reduced thermal hysteresis activities; (4) mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis activities, (5) mutants that exhibited complete loss of antifreeze activity. The protein concentration used for each sample is also indicated.
Thermal Hysteresis
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (T96I)
Tag Hexahistidine
Thermal Hysteresis "In extreme cases, ice crystals of mutants Thr96Ile and Thr98Ala are circular plates similar to the mock control, indicating the complete loss of the ice-binding affinity"
Brief description
PMID: 17579720
DOI: 10.1371/journal.pone.0000548
1. Determined the 1.7 Å crystal structure of herring type II AFP(hAFP), which resembles the C-type lectins and has unique ice-binding features.
2. Identified the ice-binding site of hAFP consisting of Thr96, Thr98, and Ca²⁺ coordinating residues Asp94 and Glu99, and the Ca²⁺ ion strengthens the interaction with ice.
3. Phylogenetic analysis showed that all type II AFPs evolved from a common ancestor and developed different ice-binding modes, originating from an ancestral duplication of a gene encoding a mannose or galactose-binding lectin.

AFP012000029

Mutation T98A
Sequence
Ice crystal morphology
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (T98A)
Tag Hexahistidine
Ice crystal morphology Fig.7.B.(5) Ice crystal morphologies of hAFP and its mutants. Samples were: (1) buffer alone and wild-type hAFP; (2) the mutant that exhibited no effect on thermal hysteresis; (3) mutants that showed reduced thermal hysteresis activities; (4) mutants which retained the ability to modify the ice crystal with no detectable thermal hysteresis activities, (5) mutants that exhibited complete loss of antifreeze activity. The protein concentration used for each sample is also indicated.
Thermal Hysteresis
PMID 17579720
DOI 10.1371/journal.pone.0000548
Protein Name hAFP (T98A)
Tag Hexahistidine
Thermal Hysteresis "In extreme cases, ice crystals of mutants Thr96Ile and Thr98Ala are circular plates similar to the mock control, indicating the complete loss of the ice-binding affinity"
Brief description
PMID: 17579720
DOI: 10.1371/journal.pone.0000548
1. Determined the 1.7 Å crystal structure of herring type II AFP(hAFP), which resembles the C-type lectins and has unique ice-binding features.
2. Identified the ice-binding site of hAFP consisting of Thr96, Thr98, and Ca²⁺ coordinating residues Asp94 and Glu99, and the Ca²⁺ ion strengthens the interaction with ice.
3. Phylogenetic analysis showed that all type II AFPs evolved from a common ancestor and developed different ice-binding modes, originating from an ancestral duplication of a gene encoding a mannose or galactose-binding lectin.