engleski

Quantum mechanical study of secondary structure formation in protected dipeptides

An extensive computational study of the conformational preferences of three capped dipeptides: Ac-Xxx-Phe-NH2, Xxx = Gly, Ala, Val is reported. On the basis of local second-order Møller–Plesset perturbation theory (LMP2) and DFT computations we were able to identify the experimentally observed conformers as L–L(g-) and -turn I(g+) in Ac-Gly-Phe-NH2, and Ac-Ala-Phe-NH2, and as the closely related L(g+)–L(g-) and -turn I(a, g+) in Ac-Val-Phe-NH2. In contrast to the experimental observation that peptides with bulky side chain have a propensity for -turns, we show that in Ac-Val-Phe-NH2 the minimum energy structure corresponds to the experimentally non detected -strand.

secondary structure ; protected dipeptides

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