The nitrate reductase inactivating factor in cultured rice cells was purified 320-fold. The purification procedure involved precipitation with (NH4)2SO4, fractionation at pH 4.0, adsorption on CM-cellulose, and gel filtration on Sephadex G-200. The molecular weight was estimated to be 200,000 from the Sephadex G-200 gel filtration.The inactivating factor shows maximal activity at pH 8.0 and appears to be located in the cytoplasm of the cultured rice cells. The inactivating factor was more stable to heat treatment than NADH nitrate reductase. The factor inactivated nitrate reductase complex except for reduced methylviologen nitrate reductase. It had no influence on the activity of nitrite reductase, glutamate dehydrogenase, and NADH diaphorase, but inactivated xanthine oxidase. The inactivating factor had no protease activity when casein, bovine serum albumin, or nitrate reductase fraction was used as the substrate. The type of inactivation of nitrate reductase by the inactivating factor was noncompetitive. Inhibition of the inactivating factor by o-phenanthroline, EDTA, and p-chloromercuribenzoic acid suggested the involvement of a metal and sulfhydryl group at its active site.
|ジャーナル||Plant and Cell Physiology|
|出版ステータス||Published - 1977 8月 1|
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