The formation of heterodimers by vancomycin group antibiotics

The formation of heterodimers in mixtures of glycopeptide antibiotics has b een detected by electrospray ionization mass-spectrometry (ESI-MS), and dim erization constants have been determined. By using NMR spectroscopy, it has been shown that these heterodimers indeed exist in aqueous solution. The d imerization constants obtained by NMR spectroscopy are in good agreement wi th those determined by ESI-MS. Structural information on the heterodimer in terface of some of the heterodimers is obtained by using two-dimensional NM R techniques and reveals that these heterodimers are similar in structure t o the homodimers.