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The Stability of C α Peptide Radicals: Why Glycyl Radical Enzymes?
Author(s) -
Hioe Johnny,
Savasci Gökcen,
Brand Harald,
Zipse Hendrik
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201002620
Subject(s) - dipeptide , radical , chemistry , phenylalanine , peptide , glycine , alanine , tyrosine , stereochemistry , amino acid , organic chemistry , biochemistry
The conformational space of dipeptide models derived from glycine, alanine, phenylalanine, proline, tyrosine, and cysteine has been searched extensively and compared with the corresponding C α dipeptide radicals at the G3(MP2)‐RAD level of theory. The results indicate that the (least‐substituted) glycine dipeptide radical is the thermochemically most stable of these species. Analysis of the structural parameters indicates that this is due to repulsive interactions between the C α substituents and peptide units in the radical. A comparison of the conformational preferences of dipeptide radicals and their closed‐shell parents also indicates that radical stability is a strongly conformation‐dependent property.