Affinity chromatography of glycopeptide antibiotics

Abstract An affinity support was designed to facilitate the isolation and purification of glycopepetide antibiotics by mimicking their known affinity for the bacterial cell wall. Members of th is 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 α-N-Ac— l -Lys— d — d -Ala) were immobilized on a N-hydroxysuccinimide-activated agarose support and evaluated using the glycopeptides vacomycin 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.