FABATINS - NEW ANTIMICROBIAL PLANT PEPTIDES

Two new antimicrobial peptides related to the gamma-thionine family ha ve been isolated by acid extraction from the broad bean Vicia faba. Th e extract was separated by ion exchange chromatography, and a fraction showing antibacterial activity was further purified by reverse-phase HPLC. Material from a single HPLC peak was sequenced and revealed the presence of two peptides differing by one amino acid. The peptides wer e named fabatins. They are 47 amino acids long, have an overall positi ve charge and contain 8 cysteines that probably form 4 disulfide bridg es characteristic of the gamma-thionins. Fabatins were active against both Gram-negative and Gram-positive bacteria, but were inactive again st the yeasts Saccharomyces cerevisiae and Candida albicans.