Behaviour of the NO - P - D - Glucosiduronic Acid of N - Acetyl - N - phenylhydroxylamine as a Substrate for p - Glucuronidase

1. Biosynthetic sodium (N-acetyl-N-phenylhydroxylamine NO-f-D-glucosid)uronate is hydrolysed completely by purified mouse urinary fl-glucuronidase into the products N-acetyl-N-phenylhydroxylamine and glucuronic acid. The hydrolysis is inhibited by saccharo-(1 -*4)-lactone. These results not only confirm the identity and purity of the substrate but also establish it as a substrate for :-glucuronidase. 2. Mammalian and bacterial f-glucuronidase preparations hydrolysed the substrate at a rate one-fifth of that for (phenolphthalein fl-Dglucosid)uronic acid under the optimum conditions of hydrolysis for each source. 3. The pH optimum is 4-1 and the Michaelis constant, Ki,, is 3-3 x 10-4M with purified mouse urinary P-glucuronidase as the enzyme source acting on the NO-p-Dglucosiduronic acid. The aglycone after extraction into chloroform was quantitatively determined spectrophotometrically at its absorption maximum (256mpu). 4. The hydrolysis was studied as a function of time and temperature. 5. From a consideration of the chemical and enzymic properties of this NO-fl-D-glucosiduronic acid it is possible to suggest its catabolism in vivo.