Deacylation of A21978C, an acidic lipopeptide antibiotic complex, by Actinoplanes utahensis

A21978C, produced by Streptomyces roseosporus NRRL 11379, is an acidic lipopeptide antibiotic complex that inhibits Gram-positive bacteria. Individual factors of the complex possess an identical peptide core or "nucleus", and are differentiated by the distinctive fatty acid acyl group attached to the N-terminus of the nucleus. Certain members of the family Actinoplanaceae deacylated A21978C to yield the unaltered nucleus, which was then reacylated to form new analogs. Actinoplanes utahensis NRRL 12052 was the most efficient of these cultures, producing up to 500 micrograms of nucleus per ml of culture broth per hour. Eacylation was also accomplished with semi-pure and tert-butoxycarbonyl (tert-BOC)-A21978C. In the latter, the ornithine amino group was blocked to prevent formation of diacyl analogs during reacylation. The acylase was an endoenzyme present in submerged cultures of A. utahensis from less than 18 to greater than 168 hours of incubation. Whole cells suspended in phosphate buffer or entrapped in polyacrylamide gel also deacylated A21978C efficiently.