ABORYCIN - A TRICYCLIC-21-PEPTIDE ANTIBIOTIC ISOLATED FROM STREPTOMYCES-GRISEOFLAVUS

The screening for growth inhibitors against Bacillus subtilis revealed a peptide antibiotic produced by Streptomyces griseoflavus TO 4072. V ery high yields of the antibiotic named aborycin were obtained by cult ivation in a medium containing soybean meal and sucrose. Isolation fro m the mycelium was carried out by a combination of extraction and gel chromatography. Preparative HPLC yielded the uniform antibiotic. The s tructure elucidation was based on GC amino acid analysis on a chiral p hase, automated Edman degradation, electrospray tandem mass spectromet ry and two-dimensional NMR (TOCSY, ROESY, HSQC, HMBC). Aborycin repres ents a 21-peptide that is cyclized f rom the side chain of Asp9 to the N-terminus of Cys1. Two disulfide bonds Cys1 to Cys13 and Cys7 to Cys 19 form a tricyclic structure consisting exclusively of protein amino acids. The peptide antibiotic aborycin was found to be identical with a HIV protease inhibitor isolated recently from Streptomyces SP 9440.