Studies on Respiratory Enzymes in Rice Kernel

Abstract

A procedure developed for the isolation and purification of soluble hemoproteins from rice embryo has been applied for the same purpose for rice bran. The method involved extraction with dilute phosphate buffer, fractionation with ammonium sulfate, ion-exchange chromatography on CM-Sephadex C-50, and gel filtration chromatography on Sephadex G-75. Cytochrome c and a blue protein were obtained as the major soluble basic proteins. Rice bran cytochrome c was crystallized from ammonium sulfate solution. The absorption spectrum and other physico-chemical properties were found to be identical with those of rice embryo cytochrome c as reported in the previous paper. The blue protein was obtained in a highly purified form. The absorption spectrum of the oxidized form shows major bands at 280 and 600 mµ with a hump around 450 mμ. The blue protein was reduced by dithionite, ascorbate, hydroquinone with a concominant disappearance of its color, but the reduced form could not be oxidized by the molecular oxygen. The molecular weight was estimated approximately 23,000 according to the Archbald method. The pigment was a weakly basic protein containing copper and gave a positive test for carbohydrate.