Crambe Thioglucoside Glucohydrolase (EC 3.2.3.1): Separation of a Protein Required for Epithiobutane Formation

Abstract

Sonicated extract of crambe seed meal prepared in the presence of ferrous ion and dithiothreitol enzymatically converts epi-progoitrin to glucose, HSO₄⁻, and a mixture of 1-cyano-2-hydroxy-3,4-epithiobutanes (50–70%) and 1-cyano-2-hydroxy-3-butene (30–50%). A fraction of the extract precipitating between 60 and 70% saturated ammonium sulfate contains thioglucosidase that converts epi-progoitrin essentially to 1-cyano-2-hydroxy-3-butene. Chromatography (on cross-linked dextran) of a 40–60% ammonium sulfate fraction leads to separation of a proteinaceous material (s₂₀ = 2.6 S) that does not hydrolyze epi-progoitrin but, in the presence of thioglucosidase, promotes the formation of 1-cyano-2-hydroxy-3,4-epithiobutanes in amounts proportional to those from crude seed meal extract.