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-cαh 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 Dab8óDab9 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