An Application of Distance Geometry to the Conformational Analysis of Rifamycin SV

Abstract

The three-dimensional structure of rifamycin SV in solution was constructed by the combination of distance geometry and NMR spectroscopy. The dihedral angles derived from the analysis of the vicinal coupling constants and NOEs were used to restrict the possible conformations of the ansa chain moiety. The restricted spatial arrangements of the ansa chain and the naphthohydroquinone ring were demonstrated by the NOEs observed at H3 on irradiating 20-CH3, 24-CH3 and 26-CH3 group. Based on the above observation a set of the upper and the lower bounds of the interatomic distances was assigned and converted to the corresponding three-dimensional coordinates. Fig. 3 shows the three-dimensional drawing of the resulting geometry, which is consistent with the observed NMR data as shown in Tables 1 and 2. © 1986, The Chemical Society of Japan. All rights reserved.