Open AccessHandedness of crossover connections in beta sheets.
Author(s) -
Jane S. Richardson
Publication year - 1976
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.73.8.2619
Subject(s) - crossover , beta sheet , loop (graph theory) , beta (programming language) , twist , folding (dsp implementation) , connection (principal bundle) , protein folding , chain (unit) , protein structure , crystallography , polypeptide chain , combinatorics , physics , chemistry , mathematics , geometry , computer science , nuclear magnetic resonance , biochemistry , amino acid , engineering , structural engineering , artificial intelligence , astronomy , programming language
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.