Myrosinase from Sinapis alba L.: A New Method of Purification for Glucosinolate Analyses

Myrosinase from white mustard seeds (Sinapis alba) has been purified starting from aqueous crude extract in a single step by affinity chromatography on Con A-Sepharose. The specific activity, recovery, and binding capacity in four separate trials using glucose, mannose, methyl a-D-glucoside, and methyl a-D-mannoside for elution were also determined. The enzyme isolated by our approach showed a good degree of purification, appearing homogeneous on SDS-PAGE analyses. In the four trials of purification, the specific activity and recovery ranged from ca. 21 800 to 26000 U/mg and 39.2 to 91.1%, respectively. The binding capacity of Con A-Sepharose for myrosinase was 6.6 mg/mL gel bed, which corresponds to 15oOOO U/mL of chromatographic bed. In addition, the enzyme bound in a column to Con A-Sepharose remained active toward substrates. In this condition, myrosinase can therefore be useful for routine analyses of total glucosinolates.