Purification and characterization of α‐chaconinase of Gibberella pulicaris

The potato pathogen Gibberella pulicaris ( Fusarium sambucinum ) is able to metabolize the potato saponin α‐chaconine by first removing the 1,2‐bound l ‐rhamnose. The catalyzing enzyme, α‐chaconinase, is inducible by the substrate and α‐solanine and α‐tomatine. The protein with a molecular mass of about 95 kDa was purified by fractionated ammonium sulfate precipitation followed by concanavalin A‐Sepharose chromatography and chromatofocusing. The enzyme is active over a wide pH and temperature range and is highly substrate specific for α‐chaconine with a K m value of 0.97 mM and V max of 37.13 nkat. α‐Solanine and α‐tomatine are not converted by the enzyme.