Structure-function relationships in a winter flounder antifreeze polypeptide. I. Stabilization of an alpha-helical antifreeze polypeptide by charged-group and hydrophobic interactions.
Structure-function relationships in a winter flounder antifreeze polypeptide. I. Stabilization of an alpha-helical antifreeze polypeptide by charged-group and hydrophobic interactions.
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冬鲽抗冻多肽的结构-功能关系。
DOI：
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发表时间：
1989
影响因子：
4.8
通讯作者：
Choy L. Hew
中科院分区：
文献类型：
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作者：
Avijit Chakrabartty;Vettai S. Ananthanarayanan;Choy L. Hew
冬季比目鱼的主要抗冻多肽（AFP）是一个单一的α -螺旋（37个氨基酸残基）。天冬氨酸和精氨酸分别位于氨基端和羧基端。这些带电荷的氨基酸是通过电荷偶极相互作用稳定AFP的α -螺旋构象的理想位置（Shoemaker, k.r., Kim, p.s., York, e.j., Stewart, j.m., Baldwin, r.l. (1987) Nature 326, 563-567）。为了了解这些和其他维持AFP结构的分子相互作用，我们进行了AFP类似物的化学合成，并通过圆二色光谱评估了它们的构象。我们合成了整个AFP分子（37-mer）和6个cooh末端肽片段（36-,33-,27-,26-，16-和15-mers）。含有酸性nh2末端残基的肽段比含有中性nh2末端残基的肽段具有更好的螺旋形成和热稳定性。pH > 9.2时螺旋形成最多。肽构象对离子强度的变化也表现出ph依赖的敏感性。在乙腈的存在下，螺旋形成减少。我们得出结论，AFP螺旋最有可能通过以下方式稳定：末端带电氨基酸与螺旋偶极子之间的电荷偶极相互作用，Lys18和Glu22之间的电荷相互作用（盐桥或氢键），以及疏水相互作用。
The major antifreeze polypeptide (AFP) from winter flounder (37 amino acid residues) is a single alpha-helix. Aspartic acid and arginine are found, respectively, at the amino and carboxyl-termini. These charged amino acids are ideally located for stabilizing the alpha-helical conformation of this AFP by means of charge-dipole interaction (Shoemaker, K. R., Kim, P.S., York, E.J., Stewart, J. M., and Baldwin, R. L. (1987) Nature 326, 563-567). In order to understand these and other molecular interactions that maintain the AFP structure, we have carried out the chemical synthesis of AFP analogs and evaluated their conformations by circular dichroism spectroscopy. We synthesized the entire AFP molecule (37-mer) and six COOH-terminal peptide fragments (36-, 33-, 27-, 26-, 16-, and 15-mers). Peptides containing acidic NH2-terminal residues displayed greater helix formation and thermal stability compared to those peptides of similar size, but with neutral NH2-terminal residues. Helix formation was maximum above pH 9.2. The peptide conformations also displayed a pH-dependent sensitivity to changes in ionic strength. Helix formation was reduced in the presence of acetonitrile. We conclude that the AFP helix is most likely stabilized by: charge-dipole interactions between charged terminal amino acids and the helix dipole, a charge interaction between Lys18 and Glu22 (either a salt bridge or a hydrogen bond), and hydrophobic interactions.