HELIX GEOMETRY IN PROTEINS
HELIX GEOMETRY IN PROTEINS
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DOI：
10.1016/0022-2836(88)90641-9
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发表时间：
1988-06-05
影响因子：
5.6
通讯作者：
THORNTON, JM
中科院分区：
文献类型：
--
作者：
BARLOW, DJ;THORNTON, JM
在本报告中，我们描述了在57种已知蛋白质晶体结构中发现的所有螺旋的一般调查，以及48种α-螺旋的详细分析。在16个被确定为高分辨率的结构中发现了螺旋。所有螺旋的扫描显示总共291个α-螺旋，71 310-螺旋和没有π-的实例螺旋观察到的螺旋的构象是显着不同的“理想”的线性结构。平均值. vphi.，. ψ。α-在蛋白质中发现的310-螺旋分别是（-62 °，-41 °）和（-71 °，-18 °）。一个计算机程序，HBEND，是用来表征和量化不同类型的螺旋扭曲。α-螺旋分为规则或不规则，线性，弯曲或扭结。在48 α中，螺旋分析，只有15%被认为是线性的，17%是扭结的，58%是弯曲的。螺旋的曲率是由螺旋的相对面上的肽氢键的差异引起的，反映了暴露的残基的羰基-溶剂/侧链相互作用，以及疏水核心中涉及的残基的包装约束。扭结螺旋的出现是由于包含脯氨酸残基，或由于螺旋侧链的最佳包装的冲突要求。在α中-对于存在由脯氨酸残基引起的扭结的螺旋，我们表明扭结的角度相对恒定（约26 °），并且螺旋氢键的破坏最小。负责扭结的脯氨酸残基是高度保守的，这表明这些扭曲可能是结构/功能上重要的。
In this report we describe a general survey of all helices found in 57 of the known protein crystal structures, together with a detailed analysis of 48 .alpha.-helices found in 16 of the structures that are determined to high resolution. The sruvey of all helices reveals a total of 291 .alpha.-helices, 71 310-helices and no examples of .pi.-helices. The conformations of the observed helices are significantly different from the "ideal" linear structures. The mean .vphi., .psi. angles for the .alpha.- and 310-helices found in proteins are, respectively, (-62.degree., -41.degree.) and (-71.degree., -18.degree.). A computer program, HBEND, is used to characterize and to quantify the different types of helix distortion. .alpha.-Helices are classified as regular or irregular, linear, curved or kinked. Of the 48 .alpha.-helices analysed, only 15% are considered to be linear; 17% are kinked, and 58% are curved. The curvature of helices is caused by differences in the peptide hydrogen bonding on opposite faces of the helix, reflecting carbonyl-solvent/side-chain interactions for the exposed residues, and packing constraints for residues involved in the hydrophobic core. Kinked helices arise either as a result of included proline residues, or because of conflicting requirements for the optimal packing of the helix side-chains. In .alpha.-helices where there are kinks caused by proline residues, we show that the angle of kink is relatively constant (.apprx.26.degree.), and that there is minimal disruption of the helix hydrogen bonding. The proline residues responsible for the kinks are highly conserved, suggesting that these distortions may be structurally/functionally important.