Affinity chromatography of glycopeptide antibiotics

An affinity support was designed to facilitate the isolation and purification of glycopeptide antibiotics by mimicking their known affinity for the bacterial cell wall. Members of this class of antibiotics inhibit peptidoglycan biosynthesis by specifically binding to pentapeptide precursors terminating with L-Lys-D-Ala-D-Ala. A series of ligands (Gly, D-Ala, D-Ala-D-Ala and alpha-N-Ac-L-Lys-D-Ala-D-Ala) were immobilized on an N-hydroxysuccinimide-activated agarose support and evaluated using the glycopeptides vancomycin and the aridicin complex. Conditions were developed to enable complete adsorption and efficient elution of both antibiotics. Of the four ligands, the readily available dipeptide offered the best compromise between high binding specificity and recovery on elution. Binding and subsequent high recovery of biologically active products were observed for eight other glycopeptide antibiotics. Column performance was shown by purification of vancomycin directly from a low titer fermentation broth. The applicability of this technique to large scale isolation was demonstrated by the preparative affinity chromatography of 36 g of the aridicins.