Purification and characterization of α-chaconinase of<i>Gibberella pulicaris</i>

Abstract

The potato pathogen &lt;it&gt;Gibberella pulicaris&lt;/it&gt; (&lt;it&gt;Fusarium sambucinum&lt;/it&gt;) is able to metabolize the potato saponin α-chaconine by first removing the 1,2-bound &lt;scp&gt;l&lt;/scp&gt;-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 &lt;it&gt;K&lt;/it&gt;&lt;inf&gt;m&lt;/inf&gt; value of 0.97 mM and &lt;it&gt;V&lt;/it&gt;&lt;inf&gt;max&lt;/inf&gt; of 37.13 nkat. α-Solanine and α-tomatine are not converted by the enzyme.