Aggregation, binding, and dimerisation studies of a teicoplanin aglycone analogue (LY154989)

LY154989 is a vancomycin group antibiotic closely related in structure to teicoplanin aglycone. In view of the clinical importance of teicoplanin, the dimerisation, aggregation, and binding of bacterial cell wall analogues by LY154989 are of interest. These properties have been studied by proton NMR spectroscopy. LY154989 has been shown to form concentration-dependent aggregates in aqueous solution, similar to those of teicoplanin, even though it does not possess a C11 acyl chain, which was hitherto thought to be the cause of this aggregation. The aggregation can be disrupted by the addition of bacterial cell wall precursor analogues such as Ac2-KDADA, Ac-DADA or Ac-DA. Thus, growing bacteria may disrupt aggregates of teicoplanin and LY154989. LY154989 dimerises weakly in aqueous solution and the dimerisation is weakly cooperative with ligand binding.