Further purification and characterization of macromomycin

The antitumor polypeptide, macromomycin (MCR) produced by Streptomyces macromomyceticus, was purified by ammonium sulfate precipitation, ultrafiltration and chromatographic techniques using Amberlite IRA-410, DEAE Sephadex A-25 (CI- and OH-type) and Sephadex G-50. Purified MCR was obtained as a white powder by lyophilization. MCR, thus purified, exhibited a single peak on Sephadex G-50 chromatography with no detectable contaminant by ultracentrifugation and polyacrylamide gel electrophoresis. MCR is an acidic polypeptide having an isoelectric point of pH 5.4. It contains no arginine and methionine. The molecular weight was 11,700, 12,500 and 11,400 by amino acid composition, gel filtration and analytical ultracentrifugation, respectively. MCR is labile as a lyophilized powder but is successfully stabilized by the addition of maltose.