Variants of 310-helices in proteins
Variants of 310-helices in proteins
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DOI：
10.1002/prot.10184
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发表时间：
2002-08-15
影响因子：
2.9
通讯作者：
Chakrabarti, P
中科院分区：
文献类型：
--
作者：
Pal, L;Basu, G;Chakrabarti, P
对最短的3（10）-螺旋（包含三个螺旋残基和参与两个连续i + 3 -> i氢键的两个侧翼加帽残基）的分析表明，并非所有螺旋都属于经典的3（10）-螺旋，其中三个中心残基采用右手螺旋构象（α（R））。确定的三种变体是：3（10）（L-）螺旋，所有残基均位于左手螺旋区域（α（L）），3（10）（EL）-螺旋，其中第一个残基位于延伸区域，随后是α构象中的两个残基，及其镜像，3（10）（E 'R）-螺旋。在这些螺旋的上下文中，以及α-螺旋的等价变体，在蛋白质结构中的二级结构的手性的长度依赖性进行了讨论。在不同类型的3（10）-螺旋中，不同位置的氨基酸偏好存在相当大的差异。每种类型的3（10）-螺旋可以被认为是由特定类型的β-转角（由残基i至i + 3组成）的延伸组成，使得第（i + 3）个残基呈现与前一个残基相同的构象。在i和i + 3位置的不同残基偏好似乎决定了在折叠结构中四个残基的特定延伸是β-转角还是3（10）-螺旋。
An analysis of the shortest 3(10)-helices, containing three helical residues and two flanking capping residues that participate in two consecutive i + 3 --> i hydrogen bonds, shows that not all helices belong to the classic 3(10)-helix, where the three central residues adopt the right-handed helical conformation (alpha(R)). Three variants identified are: 3(10)(L-)helix with all residues in the left-handed helical region (alpha(L)), 3(10)(EL)-helix where the first residue is in the extended region followed by two residues in the a, conformation, and its mirror-image, the 3(10)(E'R)-helix. In the context of these helices, as well as the equivalent variants of alpha-helices, the length dependence of the handedness of secondary structures in protein structure is discussed. There are considerable differences in the amino acid preferences at different positions in the various types of 3(10)-helices. Each type of 3(10)-helix can be thought to be made up of an extension of a particular type of beta-turn (made up of residues i to i + 3) such that the (i + 3)th residue assumes the same conformation as the preceding residue. Distinct residue preferences at i and i + 3 positions seem to decide whether a particular stretch of four residues will be a beta-turn or a 3(10)-helix in the folded structure.