Peas, glutathione reductase

The immediate product of the oxidative reaction, the monodehydroascorbate radical (Eq. [1]), is a fairly reactive and unstable species which, in the presence of a suitable reductase system, is reduced back to ascorbate. Monodehydroascorbate reductases have been identified and purified in a few cases (Ushimara et al., 1997 Dalton et al., 1992 Shigeoka et al., 1987 Borraccino et al., 1986 Hossain et al., 1984) and cDNA sequences have been published for the pea (Murthy and Zilinskas, 1994) and cucumber enzymes (Sano et al., 1995). A bacterial expression system is also available for the cucumber enzyme (Sano et al., 1995). In the absence of a suitably efficient reductase system, the monodehydroascorbate radicals disproportionate to dehydroascorbate and ascorbate in this case, ascorbate is regenerated using a glutathione-dependent dehydroascorbate reductase enzyme (Foyer and Mullineaux, 1998 and references therein). Under non-... 

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