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Valine substituted winter flounder `antifreeze': preservation of ice growth hysteresis
Author(s) -
Haymet A.D.J,
Ward Leanne G,
Harding Margaret M,
Knight Charles A
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00652-8
Subject(s) - valine , winter flounder , antifreeze protein , chemistry , antifreeze , serine , threonine , ice crystals , freezing point , flounder , residue (chemistry) , biochemistry , amino acid , biology , organic chemistry , thermodynamics , physics , fishery , fish <actinopterygii> , optics , enzyme
Three mutant polypeptides of the type I 37‐residue winter flounder `antifreeze' protein have been synthesized. All four threonine residues in the native peptide were been mutated to serine, valine and glycine respectively and two additional salt bridges were incorporated into the sequences in order to improve aqueous solubility. The peptides were analyzed by nanoliter osmometry, the `ice hemisphere' test, the `crystal habit' test, measurement of ice growth hysteresis and CD spectroscopy. While the valine and serine mutants retain the α‐helical structure, only the valine mutant retains `antifreeze' activity similar to that of the native protein. These data show that the threonine hydroxyl groups do not play a crucial role in the accumulation of the native `antifreeze' protein at the ice/water interface and the inhibition of ice growth below the equilibrium melting temperature.