Studies on Cytochrome a: XV. Cytochrome Oxidase Activity of the Okunuki Preparation and Its Activation by Heat, Alkali and Detergent Treatments*

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Abstract
The cytochrome oxidase activity of this preparation was similar to those of preparations obtained in several other laboratories for which different purification procedures were used. The pH optimum was at 5.62 in McIlvaine''s buffer at 0.04 [image] with respect to phosphate, and the maximum specific activity was F.64 sec.1Vmg protein/cuvette. Using a Na2HPO4-KH2PO4 buffer system, the highest activity was found at 0.075 [image] at pH 5.95. The activity was increased by treating cytochrome a with heat, alkali or anionic detergents. Guanidine hydrochloride had the greatest effect, increasing the specific activity to 17.1. The relationship between the physical state of cytochrome a and its activity was diBcussed.