RULES FOR ALPHA-HELIX FORMATION

我们的目标是预测自然序列的α-螺旋含量 多肽。预测规则目前正在开发和测试中。 零级规则基于标准的三个参数 螺旋-线圈转变理论(西格玛，S，德尔塔H)。最近的研究表明 在内在螺旋的形成和形成 不同氨基酸在下列情况下的变化趋势(S值) 由基于丙氨酸的参照肽中的取代来确定。这个 一阶规则包括用于侧链相互作用的附加项， 比如离子对相互作用，这是我们最近一直在研究的。 增量H，每个残基的螺旋形成的热变，是 与D·W·博伦教授合作，用热量计法测定。这个 其他参数正在根据热展开、曲线确定 用圆二色谱测定具有重复序列的多肽和 不同的链长。试衣工作是与 J.A.谢尔曼教授。作为这项工作的背景，该职位 正在研究替代的依赖性，并将其与 Lifson-Roig理论和语境依赖所预测的效果是 通过改变相邻残基进行研究。S与王健林的区别 丙氨酸多肽和主客体共聚物中的价值 羟丁基-L-谷氨酰胺(HBLG)作为宿主被认为是由一种 当HBLG是东道主时，结果对上下文有很强的依赖性。我们会 通过对语境依赖的实验来检验这一假设。

Our goal is to predict the alpha-helix contents of natural-sequence peptides. The rules for prediction are being developed and tested now. The zero-order rules are based on the three parameters of standard helix-coil transition theory (sigma,s,delta H). Recent work has shown that there are large differences between the intrinsic helix-forming tendencies (the s values) of different amino acids when these are determined by substitution in alanine-based reference peptides. The first-order rules include additional terms for side-chain interactions, such as ion pair interactions, which we have been determining recently. Delta H, the enthalpy change of helix formation per residue, is being determined calorimetrically in collaboration with Prof. D.W. Bolen. The other parameters are being determined from thermal unfolding, curves measured by circular dichroism for peptides with repeating sequences and varying chain lengths. The fitting is being done in collaboration with Prof. J.A. Schellman. As background for this work, the position dependence of a substitution is being studied in comparison with the effect predicted by the Lifson-Roig theory and the context dependence is studied by varying neighboring residues. The difference between the s values found in alanine-based peptides and in host-guest Copolymers with hydroxybutyl-L-glutamine (HBLG) as the host is thought to arise from a strong context dependence of the results when HBLG is the host. We will test this hypothesis by experiments on context dependence.