Nicotinamide Nucleotide Transhydrogenase from Vitis Vinifera CV. Raboso Grape Berries

Abstract

Some properties and characteristics of a soluble nicotinamide nucleotide transhydrogenase (TH, E.C. 1.6.1.1) from grape berries cv. Raboso, partially purified by affinity chromatography on 2',5'-ADP-Sepharose 4B followed by gel-permeation on Bio-Gel A-1.5 m are described. The maximum enzyme activity was at pH 7 and 35°C, using 3-acetylpyridine-NAD as substrate. The activity yield was 94%, the purification 34.5-fold and the molecular weight about 100 000. The Km values for NADPH and 3-acetylpyridine-NAD were approximately the same at the different purification steps. The results obtained as to the pH and temperature dependence of the enzyme activity are consistent with the perspective of immobilizing TH together with malate dehydrogenase (decarboxylating:NADP) and lactic dehydrogenase in order to obtain the decarboxylation of malic to lactic acid through the oxido-reductive capacity of TH on NADP(H) and NAD(H).