A PROTEIN CONTAINING A MOLYBDENUM COFACTOR IN WHEAT, BARLEY, AND PEA LEAVES

With increasing nitrate concentration in the medium, the activity of the Mo-co*-containing protein, capable of reducing nitroblue tetrazolium with manifestation of xanthine dehydrogenase activity on the gel after electrophoresis, is increased in wheat, barley, and pea leaves. The indicated protein is neither nitrate reductase nor xanthine dehydrogenase. Its molecular weight is about 400 kD, and its isoelectric point is 4.4 pH units. The protein is able to bind to the isotope W-185 in vitro.