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Effect of a mutation on the structure and dynamics of an α‐helical antifreeze protein in water and ice
Author(s) -
Graether Steffen P.,
Slupsky Carolyn M.,
Sykes Brian D.
Publication year - 2006
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.20889
Subject(s) - antifreeze protein , globular protein , chemistry , protein structure , molecular dynamics , biophysics , helix (gastropod) , freezing point , crystallography , psychrophile , protein dynamics , biology , biochemistry , physics , ecology , computational chemistry , thermodynamics , enzyme , snail
One strategy of psychrophilic organisms to survive subzero temperature is to produce antifreeze protein (AFPs), which inhibit the growth of macromolecular ice. To better understand the binding mechanism, the structure and dynamics of several AFPs have been studied by nuclear magnetic resonance (NMR) and X‐ray crystallography. The results have shown that different organisms can use diverse structures (α‐helix, β‐helix, or different globular folds) to achieve the same function. A number of studies have focused on understanding the relationship between the α‐helical structure of fish type I AFP and its function as an inhibitor of ice growth. The results have not explained whether the 90% activity loss caused by the conservative mutation of two threonines to serines (Thr13Ser/Thr24Ser) is attributable to a change in protein structure in solution or in ice. We examine here the structure and dynamics of the winter flounder type I AFP and the mutant Thr13Ser/Thr24Ser in both solution and solid states using a wide range of NMR approaches. Both proteins remain fully α‐helical at all temperatures and in ice, demonstrating that the activity change must therefore not be attributable to changes in the protein fold or dynamics but differences in surface properties. Proteins 2006. © 2006 Wiley‐Liss, Inc.