Total structures of 13 minor components of bacitracin (BC) were proposed, and their antimicrobial activities were investigated. The components of BCincluding bacitracins A (BC-A) and F (BC-F) were isolated by preparative HPLCand were hydrolyzed under acidic conditions.The resulting amino acids were derivatized with l-fluoro-2,4-dinitrophenyl-5-L-alanineamide and were separated by HPLCto determine their absolute configurations. It was found that the TV-terminal amino acids of BC-Aand its related components were epimerized during the hydrolysis to yield their enantiomers. The formation of these artifactual amino acids suggests that our previously proposed structures of the BCminor componentsare incorrect; therefore, the structures were corrected based on these results. The structures of the BCminor componentswere the same as that of BCs-A and -F except that one to three of the L-isoleucines, including the TV-terminal one, were replaced by L-valines. These structures were confirmed by tandem mass spectrometry under fast atom bombardment (FAB) conditions and Frit-FAB liquid chromatography/mass spectrometry. Based on the UVspectra of the BC components determined by photodiode array detection-HPLC analysis, a new systematic nomenclature was proposed for the minor components. The isolated components were also used for the determination of their minimal inhibition concentrations and it was found that BC-Ais 2~8 times more potent than the other minor componentsagainst strains of Micrococcus luteus and Staphylocoecusaureus.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.