CONFORMATIONAL-ANALYSIS OF A CYCLIC HEPTAPEPTIDE, PSEUDOSTELLARIN-D BY MOLECULAR-DYNAMICS AND MONTE-CARLO SIMULATIONS

Restrained molecular dynamics calculation in vacuo using AMBER force field implemented in MacroModel/Batchmin showed a major solution confo rmation in dimethyl sulfoxide-d(6) of pseudostellarin D, cyclo(-Gly-Ty r-Gly-Pro-Leu-Ile-Leu-). This is a cyclic heptapeptide isolated from P seudostellaria heterophylla possessing characteristics of a beta-bulge motif with three intramolecular hydrogen bonds, two beta-turns (one t ype I at Pro(4) and Leu(5) residues, and one type II at Leu(7) and Gly (1) residues) and all trans amide bonds, The solution form of pseudost ellarin D, which was homologous to that observed in the solid state, w as also supported by Monte Carlo simulation study.