Structural and functional investigation of polymyxins. ¹H NMR analysis of polymyxin B and M conformations

V. V. Okhanov, P. V. Dubovsky, A. I. Miroshnikov

All-Union Research Institute of Medicinal Plants, Moscow

Abstract: Spatial structures of two polymyxin antibiotics are compared by means of one- and two-dimensional ¹H NMR spectroscopy. Cyclic parts of polymyxins B and M contain a system of hydrogen bonds including two β-turns, however, the analysis of coupling constants ³/hn-c_αh demonstrated that torsional angles φ of peptide bonds of the residues forming β-turns in polymyxin M depend on the type of the anion. An increase in lability of the polymyxin M cyclic part in comparison with polymyxin B correlated with the selective cleavage of the peptide bond Dab⁸—Dab⁹ of this antibiotic with subtily-sine. A similar correlation was found for a short analogue of polymyxin B, a cyclo-heptapeptide.

Russian Journal of Bioorganic Chemistry 1991, 17 (12):1689-1693

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