The enzymic synthesis of aryl sulphamates. 3. The specificity and mechanism of the activation of rat-Liver arylamine sulphokinase by 17-oxo steroids

Abstract

The kinetics of the activation of rat-liver arylamine sulphokinase by 17-oxo steroids has been investigated, and it has been shown that they are consistent with the mechanism of the activation being of a mixed type in which partial competitive and partial non-competitive components are combined. The specificity of the activating effect has been studied and it has been shown that the structural requirements for activation are fairly stringent. A double bond in the D ring of the 17-oxo steroid gives an inactive compound. A substituent in the 16 position ([alpha] or[beta]) may or may not elimate the effect of the 17-oxo group. 16-substituted 17-oxo steroids which are without effect or which inhibit arylamine sulpho-kinase may still combine with the enzyme but because of the relative magnitudes of the various velocity and dissociation constants activation does not occur. The structures of the A and C rings of the steroid influence the activating effects of 17-oxo steroids.