Enzymatic Degradation of Colistin Isolation and Identification of α-N-Acyl α, γ-Diaminobutyric Acid and Colistin Nonapeptide

Abstract

Colistin, a fatty acyl peptide antibiotic, was attacked by proteolytic enzymes such as papain, ficin and bromelain, and as degradation product, a peptide portion retaining the ring structure of colistin was liberated. In contrast, an analogous antibiotic polymyxin B showed a characteristic resistance to the catalytic activity of papain.
Colistin nonapeptide and α-N-fatty acyl α, γ-diaminobutyric acid were obtained as products from the above enzymatic hydrolyzates of colistin and their chemical and physicochemical properties were investigated.
Contrary to colistin, this colistin nonapeptide was inactive to Escherichia coli. NIHJ and to many other strains even at a concentration of 800mcg/ml by the agar dilution method. As α-N-fatty acyl α, γ-diaminobutyric acid which is rest part of colistin was added to colistin nonapeptide, antimicrobial activity of colistin nonapeptide did not increase.