In vitro effect of alloxan on Na(+)-K(+)-ATPase and succinate dehydrogenase activities in brain and liver of mice.

The present study reports in vitro inhibition of the activities of enzymes Na(+)-K(+)-ATPase and succinate dehydrogenase by alloxan in brain and liver homogenates of Swiss mice. The Vmax of both the enzymes was reduced in presence of alloxan without any substantial alteration in Km for substrate. Lineweaver Burk's plots showed higher 1/Vmax for alloxan treated samples and convergence of both slopes to intercept-1/Km. The observations pointed to non-competitive type inhibition of the enzymes by alloxan. This may be due to the modification of essential--SH groups present within/adjacent to substrate binding sites by alloxan.