[Beta-cyanoalanine synthase from white lupin: some catalytic properties].

Highly purified beta-cyanoalanine synthase was prepared from 11-day-old etiolated sprouts of white lupine in the presence of diisopropylfluorophosphate. The enzyme preparations were homogeneous during polyacrylamide gel electrophoresis; their specific activity exceeded that of the blue lupine enzyme 100-fold. The purification procedure included preparation of mitochondrial acetonated powder, isolation of enzyme, chromatography on DEAE-Sephadex A-50, fractionation on Sephadex G-100 and preparative polyacrylamide gel electrophoresis. Some physico-chemical and catalytic properties of the enzyme, e. g. stability upon storage, pH optimum, isoelectric point, amino acid composition, effect of buffers on the enzyme activity, substrate and cosubstrate specificity, etc., were studied. Some properties of the enzyme were found different from those of the blue lupine enzyme. The Km values for the substrates and cosubstrates of cyanoalanine synthase were determined. The effects of some anions and cations on the enzyme activity are described.