title: Partial purification and properties of L-2,4-diaminobutyric acid activating enzyme from a polymyxin E producing organism.
abstract: An L-2,4-diaminobutyric acid activating enzyme was found in crude extracts of Aerobacillus polyaerogenes, which produces polymyxin E1 and E2. The enzyme was partially purified by sonication of the cells, followed by ultracentrifugation, ammonium sulfate fractionation, and DEAE-cellulose column chromatography. In addition to L-2,4-diaminobutyric acid, the enzyme activated L-leucine and L-threonine, which are constituent amino acids of polymyxin E. All three amino acids were bound to the enzyme as thioesters. These results suggest that polymyxin is synthesized by a multienzyme thiotemplate mechanism, in the same way as gramicidin S, tyrocidines, bacitracins, and gramicidin A.
mesh_terms: D001406:Bacillaceae / Q000201:enzymology*; D003091:Colistin / Q000096:biosynthesis*; D007700:Kinetics; D010453:Peptide Synthases / Q000302:isolation & purification / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D010453:Peptide Synthases; D003091:Colistin