PURIFICATION AND CHARACTERIZATION OF ALPHA-CHACONINASE OF GIBBERELLA-PULICARIS

The potato pathogen Gibberella pulicaris (Fusarium sambucinum) is able to metabolize the potato saponin alpha-chaconine by first removing th e 1,2-bound L-rhamnose. The catalyzing enzyme, alpha-chaconinase, is i nducible by the substrate and alpha-solanine and alpha-tomatine. The p rotein with a molecular mass of about 95 kDa was purified by fractiona ted ammonium sulfate precipitation followed by concanavalin A-Sepharos e chromatography and chromatofocusing. The enzyme is active over a wid e pH and temperature range and is highly substrate specific for alpha- chaconine with a K-m value of 0.97 mM and V-max of 37.13 nkat. alpha-S olanine and alpha-tomatine are not converted by the enzyme. (C) 1998 F ederation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.