[Specific protection by sulfhydryl groups against inhibition of urease by hypoglycaemic drugs (author's transl)].

The effect of oral hypoglycaemic drugs, derivatives of sulphonylurea, upon urease has been studied. These compounds, structurally connected to urea, produce a competitive inhibition of enzyme activity with respect to substrate. Glutathioné (reduced form) and cysteine prevent inactivation of enzyme by sulphonylurea, whereas-oxidated glutathione and cysteine do not. The same phenomenon occurs in enzyme preparations inhibited by p-hydroxymercuribenzoate. The role of sulfhydryl groups in the formation of enzyme-substrate complex is discussed.