title: Conversion of l-Sorbosone to l-Ascorbic Acid by a NADP-Dependent Dehydrogenase in Bean and Spinach Leaf.
abstract: An NADP-dependent dehydrogenase catalyzing the conversion of l-sorbosone to l-ascorbic acid has been isolated from Phaseolus vulgaris L. and Spinacia oleracea L. and partially purified. It is stable at -20 degrees C for up to 8 months. Molecular masses, as determined by gel filtration, were 21 and 29 kilodaltons for bean and spinach enzymes, respectively. K(m) for sorbosone were 12 +/- 2 and 18 +/- 2 millimolar and for NADP(+), 0.14 +/- 0.05 and 1.2 +/- 0.5 millimolar, for bean and spinach, respectively. Lycorine, a purported inhibitor of l-ascorbic acid biosynthesis, had no effect on the reaction.
authors: Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340.
authors: M W
authors: MW
authors: Loewus
authors: D L
authors: DL
authors: Bedgar
authors: K
authors: K
authors: Saito
authors: F A
authors: FA
authors: Loewus