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The α‐helical conformation of the undecapeptide boc‐ l ‐Ala‐[Aib‐Ala] 2 ‐Glu(OBzl)‐Ala‐[Aib‐Ala] 2 ‐OMe: Synthesis, X‐Ray crystal structure, and conformation in solution
Author(s) -
Schmitt Heribert,
Winter Werner,
Bosch Roland,
Jung Günther
Publication year - 1982
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.198219820708
Subject(s) - chemistry , alamethicin , antiparallel (mathematics) , crystallography , crystal structure , stereochemistry , helix (gastropod) , circular dichroism , x ray , membrane , ecology , biochemistry , physics , quantum mechanics , lipid bilayer , snail , magnetic field , biology
As models of the helical N‐terminal part of alamethicin the undecapeptides Boc‐L‐Ala‐[Aib‐Ala] 2 ‐Glu(OBzl)‐Ala‐[Aib‐Ala] 2 ‐OMe ( 1 ) and Boc‐L‐Ala‐[Aib‐Ala] 2 ‐Gly‐Ala‐[Aib‐Ala] 2 ‐OMe ( 2 ) were synthesized. 1 was examined by X‐ray crystallography using direct methods for solution of the phase problem. The unit cell ( P 2 1 ) contains two antiparallel α‐helices with nine residues being part of the helix. Continuing chains of head‐to‐tail linked α‐helices are arranged in the crystal lattice. CD and 13 C NMR spectra revealed a pronounced stabilizing effect of the α‐aminoisobutyric acid residues for the α‐helical conformation in solution.