The fermentation, isolation and characterization of a macromolecular peptide antibiotic: AN-1

A new macromolecular peptide antibiotic, named AN-1, was isolated from the culture broth of Streptomyces albus AJ9003. From 18 liters of culture broth (110 units/ml activity) a 300 mg sample of AN-1 was obtained with a specific activity of 1,160 units/mg was obtained. AN-1 is a basic polypeptide with a molecular weight of 12,000, isoelectric point of pH 8.3, and gives a single band on SDS polyacrylamide gel electrophoresis. It is soluble in water but insoluble in ethanol, butanol and acetone. It was stable at pH 6 approximately 9 but very unstable at pH 2. The UV absorption spectrum shows a maximum at 280 nm. AN-1 had no antibacterial activity against the Gram-positive and Gram-negative bacteria tested, but shows strong inhibitory activity toward Escherichia coli MP2, a macromolecule permeable mutant. In addition to being highly mutagenic, AN-1 inhibits the in vitro cell growth of L1210 (ED50 0.41 micrograms/ml). However, AN-1 had no antitumor activity against mouse leukemia L1210 or Lewis lung carcinoma in mouse.