A NOVEL ANTIMICROBIAL PEPTIDE FROM THE LOACH, MISGURNUS-ANGUILLICAUDATUS

A novel antimicrobial peptide, named misgurin, was isolated and charac terized from the leach (mudfish), Misgurnus anguillicaudatus. The 21-a mino-acid peptide with a molecular mass of 2502 Da was purified to hom ogeneity using a heparin-affinity column and C18 reverse-phase and gel -permeation highperformance liquid chromatography. The complete amino acid sequence of misgurin, which was determined by an automated amino acid sequencer, was s-Phe-Ser-Lys-Lys-Gly-Ala-Ala-Ala-Arg-Arg-Arg-Lys. Misgurin is a strongly basic peptide which has 5 arginine and 4 lysin e residues, Comparison of the amino acid sequence with those of other known antimicrobial peptides revealed that misgurin was a novel antimi crobial peptide. Misgurin showed a strong antimicrobial activity in vi tro against a broad spectrum of microorganisms without significant hem olytic activity and was about 6 times more potent than magainin 2. Sca nning electron microscopy confirmed that the peptide caused damage to the cell membrane by a pore-forming mechanism similar to that of magai nin 2. This damage occurred at the minimal inhibition concentration (M IC), but at higher concentration than MIC it lysed the cell. (C) 1997 Federation of European Biochemical Societies.