Abstract
A commercial colistin was fractionated by countercurrent distribution into three different peptides. Paper chromatography showed these peptides corresponded to colistin A, B and C.
On acid hydrolysis both colistin A and B gave DAB 6, L-threonine 2, L-leucine I and D-Ieucine 1. From the ether extracts of colistin A hydrolysate MOA was isolated, and IOA from colistin B.
Molecular weights of colistins were deter-mined by the method of partial DNP-sub-stitution and spectrophotometric measurement of the picrates and the values of about 1360 were found for both colistins A and B as their pentahydrochlorides.
The authors wish to thank Mr. T. Yano and his coworkers of Banyu Pharmaceutical Co., Ltd. for the gifts of commercial colistin, and for the test of antibacterial activity. We are indebted to Mr. Y. Yoichi of Nippon Shinyaku Co., Ltd. for the gas chromatography, Dr. H. Hatano of Department of Biochemistry, Faculty of Science, Kyoto University for amino acid analysis by amino acid analyser, Mr. S. Esaka of our laboratory for microbiological assay and the members of microanalytical center of Kyoto University for elementary analysis.
