CONDITIONS AFFECTING PURIFICATION AND SOLUTION OF A UTERINE EPINEPHRINE-OXIDIZING ENZYME

Purification and characterization of a uterine epinephrine-oxidizing enzyme have been continued in the present studies. It was reported previously that the oxidation of epinephrine by this enzyme resulted in the formation of an actomyosin adenosine triphosphatase (ATPase) inhibitor. Adrenochrome was identified as an intermediate in the reaction. New data have been obtained which confirm the formation of adrenochrome in the reaction. Progressively greater disintegration of the myometrium has resulted in increased yields and purity of the enzyme. The most striking effect, however, was the separation of a water-soluble form of the enzyme through disruption of a highpurity fraction with ultrasonic sound. Yields of water-soluble enzyme with present procedures were increased approximately 200-fold over that possible with the former methods. In addition, the activity of the water-soluble protein in terms of ATPase inhibitor formation was increased approximately 9-fold. Although the uterine oxidase was soluble in water, it was found to be insoluble at physiological ionic strengths. These observations suggest that the enzyme probably exists in association with a membrane or organelle. Reference is made to the possible role of this enzyme in relation to the negative inotropic effects of epinephrine. © 1969.