A. Hitachimycin
Hitachimycin 8.9) is an antiprotozoal antibiotic isolated from the culture broth of actinomycete strain No. KM 4927. A novel 19-membered ring lactam skeleton for hitachimycin is substantially distinguishable with ansa- mycin antibiotics 10) in the point that the antibiotic contains no aromatic or quinoid nucleus in the ansa- chain moiety. The labeling pattern by [1-13C]acetate of hitachimycin molecule indicated that the antibiotic consists of eight malonates, one methylmalonate and one phenylalanine 11) as illustrated in Fig. 1. A high level of enrichment at C-19 in the feeding experiment of conversion of D,L-C1 13C]phenylalanine suggests the in a phenylalanine to B-phenylalanine by aminomutase hitachimycin-producing strain and then its incorporation into a polyketide chain presumably as a starter unit. The occurrence of the intramolecular rearrangement of an amino group from a- to B-position was evidenced from the relative intensity with natural occurrence of the signal of an amide nitrogen atom in the 15N NMR spectrum of hitachimycin enriched with DL l-a-phenylalanine. Although tyrosine aminomutase has been reported in the biosynthesis of a peptide antibiotic, 12) the occur. edeine rence of phenylalanine aminomutase in a hitachimyci producing strain may be the first finding in microbial secondary metabolites