Theoretical conformational analysis and synthesis of analogues of the heptapeptide antibiotic K-582 A.

A detailed theoretical conformational analysis of the linear heptapeptide antibiotic [Arg2]K-582 A (Arg-Arg-D-Orn-Thr-D-Orn-Lys-D-Tyr) was carried out. The results of the computer simulation suggest that the linear peptide has a high propensity to fold in solution into a quasi-cyclic conformation in equilibrium with pi(L-D) helices. The synthesis of two inactive analogues with an L-Lys in place of D-Orn3 or D-Orn5 confirms the importance of the proposed folding pattern for the occurrence of the antimicrobial activity of K-582 A.