engleski

Folding-unfolding equilibrium of a methylidene-substituted beta-peptide

beta-Peptides possess the ability to fold into secondary structure elements, and this property, together with resistance to biodegradation, makes these compounds interesting for pharmaceutical applications. Recently. a novel class of beta-peptides containing methylidene moieties was described. The GROMOS 53A6 force field was used to simulate the folding equilibrium of a beta(3)-hexapeptide with methylidene (CH2=) groups at all six CA-atoms. Due to the rotational barriers induced by these methylidene groups, the helical secondary-structure elements. normally found in beta(3)-peptides, are disfavored in this molecule. Simulations, started from fully extended and 3(14)-helical conformations, showed that the molecule adopts a complete 2(8)-helix for ca. 5% of the time and partial 2(8)-helical conformations for ca. 20% of the time. Yet, as suggested by experiments, the folding equilibrium is dominated by unfolded conformations.

proteinogenic side-chains; gromos force-field; molecular-dynamics; secondary-structure; simulation; acid; antibacterial; stability; foldamers; valine

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