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An analysis of side chain interactions and pair correlations within antiparallel β‐sheets: The differences between backbone hydrogen‐bonded and non‐hydrogen‐bonded residue pairs
Author(s) -
Wouters Merridee A.,
Curmi Paul M. G.
Publication year - 1995
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.340220205
Subject(s) - antiparallel (mathematics) , crystallography , chemistry , directionality , beta sheet , side chain , stereochemistry , hydrogen bond , twist , folding (dsp implementation) , protein structure , molecule , physics , geometry , organic chemistry , biochemistry , biology , electrical engineering , genetics , engineering , polymer , quantum mechanics , magnetic field , mathematics
Abstract Cross‐strand pair correlations are calculated for residue pairs in antiparallel β‐sheet for two cases: pairs whose backbone atoms are hydrogen bonded together (H‐bonded site) and pairs which are not (non‐H‐bonded site). The statistics show that this distinction is important. When glycine is located on the edge of a sheet, it shows a 3:1 preference for the H‐bonded site. Thestrongest observed correlations are for pairs of disulfide‐bonded cystines, many of which adopt a close‐packed conformation with each cystine in a spiral conformation of opposite chirality to its partner. It is likely that these pairs are a signature for the family of small, cystine‐rich proteins. Most other strong positive and negative correlations involve charged and polar residues. It appears that electrostatic compatibility is the strongest factor affecting pair correlation. Significant correlations are observed for β‐ and γ‐branched residues inthe non‐H‐bonded site. An examination of the structures showsa directionality in side chain packing. There is a correlation between (1) the directionality in the packing interactions of non‐H‐bonded β‐ and γ‐branched residue pairs, (2) the handedness of the observed enantiomers of chiral β‐branched side chains, and (3) the handedness of the twist of β‐sheet. These findings have implications for the formation of β‐sheets during protein folding and the mechanism by which the sheet becomes twisted. © 1995 Wiley‐Liss, Inc.