Structiure of beta-beta-hairpins closed into cycles by S-S-bridges
Brazhnikov, E.V.; Efimov, A.V.
Molekuliarnaia Biologiia 44(3): 529-534
2010
ISSN/ISBN: 0026-8984 PMID: 20608178 Document Number: 645439
In the present study, a stereochemical analysis of proteins containing beta-beta-hairpins closed into cycles by S-S-bridges has been performed. A database of these proteins has been compiled from the Protein Data Bank (total 428 PDB entries). 390 beta-beta-hairpins closed into cycles by S-S-bridges have been found in non-homologous proteins included into the database. Analysis showed that 118 hairpins contain S-S-bridges formed by cysteins located opposite to each other in the neighboring beta-strands. Among them, 110 hairpins are left-turned and 8 beta-hairpins are right -turned when viewed from the same side where S-S-bridges are located. In the other group of 272 beta-hairpins, the S-S-bridge is formed by two cysteins one of which is located in the beta-strand and the other in the loop juxtaposed to the beta-hairpin at the N- (84%) or C-terminus (16%). As shown, in most cases the loop-hairpin region closed into a cycle by the S-S-bridge formes a turn of a left-handed superhelix.