[Properties of metlegoglobin reductase from lupin root nodules].

The interaction between metlegoglobin reductase from lupin root nodules cytosol and some substrates and inhibitors was studied. The Km values for electron acceptors: dichlorophenol indophenol, potassium ferricyanide, methylene blue and cytochrome c were 5.7 x 10(-5), 2.1 x 10(-5), 1.75 x 10(-4) and 2.5 x 10(-5) M, respectively. The Km value for electron donor NADH was 2.4 x 10(-5) M. Hydroxymercurybenzoate and ethylmaleimide inhibited the metlegoglobin reductase activity; the enzyme activity was also inhibited by NAD. Metlegoglobin reductase was inhibited by quinacrine, which confirmed the flavoproteid nature of the enzyme earlier discovered by the authors. Cytochrome b5 from rabbit liver microsomes can be an electron intermediate during cytochrome c reduction by metlegoglobin reductase. The temperature optimum of metlegoglobin reductase is 40 degrees. The enzyme is comparatively thermostable; and was inactivated by 85% only after 5 min heating at 100 degrees.