Uricase, Guanase, and Xanthine Oxidase from the Fat Body of the Cockroach, Leucophaea Maderae1

Abstract

Uricase was isolated from homogenates of the fat body of the nymph and adult cockroach, Leucophaea maderae, by the method of Praetorius (1949). Its activity is of the first-order with an average Michaelis constant of 1.7 × 10⁵ moles per liter at a pH of 9.2. Guanase was isolated from the fat body by the method of Kalckar (1947) and its activity measured spectrophotometrically. Xanthine oxidase was found in homogenates of the nymph and adult cockroach. Nymphal homogenates demonstrated a higher ability to oxidize the oxypurines than those of the adult. Homogenates of both stages were more active with hypoxanthine than with xanthine as the substrate.