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C-terminal side of α-helix is more stable than N-terminal side


THE stability of the polypeptide chain of the α-helix has been extensively studied by both experimental and theoretical examination of the transition from the α-helical to random coil conformation of different homopolypeptides1,2. In these studies, the α-helix has been treated symmetrically along the helical axis. Amino acid residues located at the nth position from the N terminus and the C terminus of the α-helix in a homopolypeptide are assumed to behave in the same manner. However, the stability of the α-helix in the N-terminal region must be different from that in the C-terminal region, due to some extent to the asymmetrical nature of the peptide bond. It has not previously been known whether or not the influence of a polypeptide in random conformation is independent of the side of the α-helix to which the polypeptide is attached. We report here the first experimental evidence for such asymmetrical behaviour.

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TAKAHASHI, S., IHARA, S. & OOI, T. C-terminal side of α-helix is more stable than N-terminal side. Nature 276, 735–736 (1978).

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