付里叶变换红外光谱法研究水在稳定多肽构象中的作用

THE ROLE OF WATER IN STABILIZING POLYPPETIDE CONFORMATION STUDIED BY FOURIER TRANSFORM INFRARED

在０—１００％相对湿度（ＲＨ）范围内用竹里叶变换红外光谱研究了水合对聚赖氨酸溴化氢结合物构象的影响。随相对湿度ＲＨ增加，水合分为：无规卷曲、β－折叠和α－螺旋三个稳定的阶段．多肽的水合行为远比报导的复杂，在三个阶段中都不是纯单一结构组分，在任何一个ＲＨ下都存在３－４个吸收组分。在ＲＨ＞４４％以上β特征吸收发生复杂变化，表明β－结构的类型可能发生变化。实验表明，水是肽链柔性的增塑剂，运动性和构象的催化剂。

The role of water in stabilizing the conformation of polylysine hydrobromide was investigatal by means of FTIR in the relative humidity rangs of 0 to 100%. With the of relative humidity, three hydration ranges were observed in which the random coil, β, or αconformation is respectively the most stable one. However, the hydrion-induced behavior of polypetide observed is much more complicated than that reports in the literature. At any relative humidity,including the one at which a given conformation is stable, three to four IR absorption bands were detected . In particular, at the relative hum,idity more than 44%,characteristic absorptions of β-structures were significatly changed , denoting a presumable change in the type of β-sheet. The results suggest that water may act as a plasticizer for the flexibility and a catalyst for mobility and conformation of peptide chain.