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Side chain–backbone hydrogen bonding contributes to helix stability in peptides derived from an α‐helical region of carboxypeptidase A
Author(s) -
Bruch Martha D.,
Dhingra Madan M.,
Gierasch Lila M.
Publication year - 1991
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.340100206
Subject(s) - helix (gastropod) , hydrogen bond , circular dichroism , chemistry , peptide , crystallography , side chain , stereochemistry , biochemistry , molecule , organic chemistry , polymer , biology , ecology , snail
Recently, Presta and Rose proposed 1 that a necessary condition for helix formation is the presence of residues at the N‐and C‐termini (called NTBs and CTBs) whose side chains can form hydrogen bonds with the initial four amides and the last four carbonyls of the helix, which otherwise lack intrahelical hydrogen bonding partners. We have tested this hypothesis by conformational analysis by circular dichroism (CD) of a synthetic peptide corresponding to a region (171–188) of the protein carboxypeptidase A; in the protein, residues 174 to 186 are helical and are flanked by NTBs and CTBs. Since helix formation in this peptide may also be stabilized by electrostatic interactions, we have compared the helical content of the native peptide with that of several modified peptides designed to enable dissection of different contributions to helix stability. As expected, helix dipole interactions appear to contribute substantially, but we conclude that hydrogen bonding interactions as proposed by Presta and Rose also stabilize helix formation. To assist in comparison of different peptides, we have introduced two concentration‐independent CD parameters which are sensitive probes of helix formation.