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The role of context on α‐helix stabilization: Host‐guest analysis in a mixed background peptide model
Author(s) -
Yang Jianxin,
Spek Erik J.,
Gong Youxiang,
Zhou Hongxing,
Kallenbach Neville R.
Publication year - 1997
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560060614
Subject(s) - helix (gastropod) , context (archaeology) , peptide , alanine , amino acid , sequence (biology) , chemistry , peptide sequence , alpha helix , side chain , block (permutation group theory) , crystallography , stereochemistry , circular dichroism , biochemistry , biology , mathematics , ecology , paleontology , geometry , organic chemistry , snail , gene , polymer
The helix content of a series of peptides containing single substitutions of the 20 natural amino acids in a new designed host sequence, succinyl‐YSEEEEKAKKAXAEEAEKKKK‐NH 2 , has been determined using CD spectroscopy. This host is related to one previously studied, in which triple amino acid substitutions were introduced into a background of Glu‐Lys blocks completely lacking alanine. The resulting free energies show that only Ala and Glu − prove to be helix stabilizing, while all other side chains are neutral or destabilizing. This agrees with results from studies of alanine‐rich peptide models, but not the previous Glu‐Lys block oligomers in which Leu and Met also stabilize helix. The helix propensity scale derived from the previous block oligomers correlated well with the frequencies of occurrence of different side chains in helical sequences of proteins, whereas the values from the present series do not. The role of context in determining scales of helix propensity values is discussed, and the ability of algorithms designed to predict helix structure from sequence is compared.