期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1976
卷号：73
期号：8
页码：2619-2623
DOI：10.1073/pnas.73.8.2619
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：In a crossover connection, the polypeptide chain leaves one end of a beta sheet, forms a loop of any length and any conformation, and reenters the same beta sheet from the opposite end. Of the 85 examples of crossover connections which occur in the known protein structures, 83 are righthanded and only two are lefthanded. It is proposed that consistent handedness, even in long irregular loops, could be produced by the preferred twist direction of extended chain and the righthandedness of alpha-helices, provided certain conditions hold during the protein folding process.
