Isolation, purification and partial amino acid sequence of a highly hydrophobic new microcin named microcin L produced by Escherichia coli

We report here the production, by an Escherichia coli strain, of two microcins, microcin J25 and a new one that we designated microcin L. The active peptides were separated by solid phase extraction on C-18 cartridges. Microcin L was then purified to homogeneity by cationic-exchange high-performance liquid chromatography. Its molecular mass, determined by mass spectrometry, is 8899 Da. The amino acid composition and the sequence of the first 40 N-terminal residues indicate that microcin L is a hydrophobic peptide, which exhibits high homology to gassericin and lactacin F which both belong to the class II bacteriocins. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.