The biochemistry of aromatic amines. 7. The enzymic hydrolysis of aminonaphthyl glucosiduronic acids

Abstract

[beta]-Glucuronidase of human urine, prepared by ultrafiltration and dialysis, hydrolyzes the O-glucosiduronic acid derivatives of phenolphthalein, 8-hydroxyquinoline, 2-acetamido-6-naphthol, 2-acetamido-1-naphthol, 1-naphthol and 2-amino-1-naphthol, although 2-amino-1-naphthyl glucosiduronic acid has a lower affinity than the other substrates. The theoretical maximum velocity of hydrolysis (Vmax.) for 2-amino-l-naphthyl glucosiduronic acid could not be determined; that for 1-naphthyl glucosiduronic acid was 1/3 of that of other substrates. The affinity of glucosaccharo-1[long dash][forward arrow]4-lactone for [beta]-glucuronidase is 1000 times as great as that of its 6-methyl and 6-ethyl esters. The inhibition of B-glucuronidase by glucosaccharo-1[forward arrow]4-lactose is much greater in the region of the optimum pH of the enzyme. The resistance of 2-amino-1-naphthylsulfate to hydrolysis by aryl sulfatase has been confirmed.