β-GLUCURONIDASE OF RABBIT POLYMORPHONUCLEAR LEUCOCYTES

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Abstract
Rabbit polymorphonuclear leucocytes contain an enzyme capable of hydrolyzing biosynthetic phenolphthalein mono-β-glucuronide. The concentration of the enzyme in the white cell is some 2000 times the concentration of the enzyme in the blood plasma. Under the conditions of study, the β-glucuronidase activity was proportional to the concentration of the enzyme. The effect of substrate concentration on the enzyme activity was studied and the Michaelis constant, Ks, determined. The course of the reaction was linear with time for the first 12 hr. and then fell off slightly during the next 12 hr. The optimum pH of the enzyme was 4.45 in either 0.2 M acetate or 0.2 M phthalate buffer. It was not inhibited by cyanide, azide, iodoacetate, fluoride, glycine, thiourea, urethane, arsanilic acid, acetophenone, o-cresol or m-cresol, in a final concentration of 0.01 M. The possible function of β-glucuronidase in rabbit polymorphonuclear leucocytes is discussed.