2 CONFORMERS OF THE GLYCOPEPTIDE ANTIBIOTIC TEICOPLANIN WITH DISTINCTLIGAND-BINDING SITES

The clinically important vancomycin group glycopeptide antibiotics, wh ich act by blocking cell wall synthesis, are crucial in the treatment of methicillin resistant Staphylococcus aureus. All of the group membe rs studied so far, with the apparent exception of teicoplanin, enhance their antibiotic action by the formation of an asymmetric homodimer. Teicoplanin exists in two main conformers which differ by a rotation o f approximately 180 degrees of a sugar residue. From NMR studies and m olecular modelling, we present structures for the two conformers and c onclude that they have different binding affinities for cell wall anal ogues. The two conformers of teicoplanin are closely analogous to thos e adopted by each half of the asymmetric dimers of the other vancomyci n group antibiotics.