FIGURE 1.

Enzymatic hydrolysis pathways of 2-propenyl glucosinolate (2Prop) and 4-(methylsulfinyl)butyl glucosinolate (4MSOB). ESP, epithiospecifier protein. The glucosinolate hydrolysis is started by myrosinase induced degradation with vitamin C being a cofactor for this enzyme. The resulting thiohydroximate-O-sulfate intermediate either spontaneously degrades to the isothiocyanate (ITC) and under acidic conditions to the nitrile. In presence of ESP, which is dependent on Fe²⁺, the formation of the epithionitrile from the alkenyl intermediate (2Prop) or of the nitrile from the non-alkenyl intermediate (4MSOB) is catalyzed.