A Diminished Role for Hydrogen Bonds in Antifreeze Protein Binding to Ice
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- 作者：Heman Chao ; Michael E. Houston ; Jr. ; Robert S. Hodges ; Cyril M. Kay ; Brian D. Sykes ; Michè ; le C. Loewen ; Peter L. Davies ; and Frank D. Sö ; nnichsen
- 刊名：Biochemistry
- 出版年：1997
- 出版时间：December 2, 1997
- 年：1997
- 卷：36
- 期：48
- 页码：14652 - 14660
- 全文大小：213K
- 年卷期：v.36,no.48(December 2, 1997)
- ISSN：1520-4995
文摘
The most abundant isoform (HPLC-6) of type I antifreeze protein(AFP1) in winter flounderis a 37-amino-acid-long, alanine-rich, 
-helical peptide, containingfour Thr spaced 11 amino acids apart.It is generally assumed that HPLC-6 binds ice through ahydrogen-bonding match between the Thr andneighboring Asx residues to oxygens atoms on the {20
1} planeof the ice lattice. The result is a loweringof the nonequilibrium freezing point below the melting point (thermalhysteresis). HPLC-6, and twovariants in which the central two Thr were replaced with either Ser orVal, were synthesized. The Servariant was virtually inactive, while only a minor loss of activity wasobserved in the Val variant. CD,ultracentrifugation, and NMR studies indicated no significantstructural changes or aggregation of thevariants compared to HPLC-6. These results call into question therole of hydrogen bonds and suggesta much more significant role for entropic effects and van der Waalsinteractions in binding AFP to ice.
-helical peptide, containingfour Thr spaced 11 amino acids apart.It is generally assumed that HPLC-6 binds ice through ahydrogen-bonding match between the Thr andneighboring Asx residues to oxygens atoms on the {201} planeof the ice lattice. The result is a loweringof the nonequilibrium freezing point below the melting point (thermalhysteresis). HPLC-6, and twovariants in which the central two Thr were replaced with either Ser orVal, were synthesized. The Servariant was virtually inactive, while only a minor loss of activity wasobserved in the Val variant. CD,ultracentrifugation, and NMR studies indicated no significantstructural changes or aggregation of thevariants compared to HPLC-6. These results call into question therole of hydrogen bonds and suggesta much more significant role for entropic effects and van der Waalsinteractions in binding AFP to ice.