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Peptide design: Crystal structure of a helical peptide module attached to a potentially nonhelical amino terminal segment
Author(s) -
Karle Isabella L.,
Rao R. Balaji,
Kaul Ramesh,
Prasad Sudhanand,
Balaram P.
Publication year - 1996
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/(sici)1097-0282(199607)39:1<75::aid-bip8>3.0.co;2-s
Subject(s) - antiparallel (mathematics) , chemistry , linker , helix (gastropod) , hydrogen bond , crystallography , peptide , stereochemistry , molecule , crystal structure , residue (chemistry) , biochemistry , physics , snail , computer science , magnetic field , biology , ecology , organic chemistry , quantum mechanics , operating system
The peptide Boc‐Gly‐Dpg‐Gly‐Val‐Ala‐Leu‐Aib‐Val‐Ala‐Leu‐OMe has been designed to examine the structural consequences of placing a short segment with a low helix propensity at the amino terminus of a helical heptapeptide module. The Gly‐Dpg‐Gly segment is a potential connecting element in the synthetic construction of a helix‐linker‐helix motif. Crystal parameters for the peptide are P2 1 , a = 8.651(3) Å, b = 46.826(13) Å, c = 16.245 Å, β = 90.13(3)*, Z = 4; 2 independent molecules/asymmetric unit. The structure reveals almost identical conformations for the two independent molecules. The backbone is completely helical for residues 2–9, with one 4 → 1 hydrogen bond and six 5 → 1 hydrogen bonds. The α,α‐di‐n‐propylglycine residue adopts a helical conformation. Gly(1) adopts an extended conformation resulting in a nonhelical N‐terminus, with the Boc group swinging away from the helix. The lateral association of helices in the b axis direction is unusual in that the helix axes are directed up or down (parallel or antiparallel) by pairs: ↓↓↑↑↓↓, etc. © 1996 John Wiley & Sons, Inc.