Induction of Unexpected Left-Handed Helidty by an N-Terminal L-Amino Acid In an Otherwise AcMral Peptide Chain

摘要

Helices composed of L-a-amino acids are typically more stable when they adopt right-handed (rather than left-handed) helicity, due to steric interactions between the L-amino acid side chains and the main-chain carbonyl groups. Left-handed helices are rare motifs in protein structures (about 0.4 % in a nonredundant subset of the Protein Data Bank), and the vast majority of these helices are short (four residues at most), stabilized by interhelical hydrogen bonds and other weak interactions.