The enzymic synthesis of aryl sulphamates

Abstract

A method is described for the assay of 2-naphthyl sulfamate synthesis by liver preparations. The determination of the sulfamate is based on the removal of free amino compounds by treatment with ion-exchange resin, hydrolysis of the sulfamate to the amino compound and its subsequent determination by diazotization and coupling with thymol. The optimum pH of the reaction is 8.2, the optimum concentration of adenosine triphosphate is 5 m[image], the optimum sulfate concentration is 10 m[image], and the optimum concentration of 2-naphthyla-mine is greater than 2 m[image]. 1-Naphthylamine and aniline are also substrates for this enzyme system, but benzylamine and glucosamine are not. The sulfamate is probably formed by the transfer of sulfate from adenosine-3[image]-phosphate 5[image]-sulfatophosphate, the transfer being catalyzed by arylamine sulfokinase, which has an optimum pH of 8.2 and requires the presence of at least 2 m[image]-Mg++ before it shows its activity. The enzyme is inhibited by p-chloromercuribenzoate and the inhibition abolished by cysteine. The rate of synthesis of 2-naphthyl sulfamate by rat-liver preparations is increased by about 400% by 17-oxo steroids in concentrations of approximately 10-5[image]. The rate of synthesis of sulfhamate by guinea pig preparations is not increased by 17-oxo steroids. It is suggested that the mechanism of this activation involves the formation of steroid 17-enol sulfates and that these enol sulfates would be a form of "active sulfate", having a high sulfate group potential. The rates of synthesis of certain other sulfate esters by the enzyme preparations are described.