Pal L, Basu G
Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VIIM, Calcutta 700 054, India.
Protein Eng. 1999 Oct;12(10):811-4. doi: 10.1093/protein/12.10.811.
The 3(10)-helix constitutes a small but significant fraction of secondary structural elements in proteins. Protein data base surveys have shown these helices to be present as alpha-helical extensions, in loops and as connectors between beta-strands. The present work focuses on two-turn and longer 3(10)-helices where we establish that two-turn and longer 3(10) helices, unlike the more abundant single-turn 3(10)-helices, frequently occur independent of any other contiguous secondary structural elements. More importantly, a large fraction of these independent two-turn and longer 3(10)-helices, along with alpha-helices and beta-strands, are found to form novel super-secondary structural motifs in several proteins with possible implications for protein folding, local conformational relaxation and biological functions.
3(10)螺旋是蛋白质二级结构元件中一小部分但却很重要的组成部分。蛋白质数据库调查显示，这些螺旋以α螺旋延伸、环以及β链之间连接子的形式存在。目前的工作聚焦于两圈及更长的3(10)螺旋，我们证实，与更为常见的单圈3(10)螺旋不同，两圈及更长的3(10)螺旋经常独立于任何其他相邻的二级结构元件而出现。更重要的是，在几种蛋白质中发现，这些独立的两圈及更长的3(10)螺旋中的很大一部分，与α螺旋和β链一起，形成了新的超二级结构基序，这可能对蛋白质折叠、局部构象弛豫和生物学功能有影响。
