Inhibition by streptozotocin of the activity of succinyl‐Co A synthetase in vitro and in vivo

Abstract

The activity of succinyl-CoA synthetase from mouse liver and kidney was inhibited by streptozotocin in vitro. Streptozotocin behaved essentially as a non-competitive inhibitor, and the following kinetic values were obtained (in the presence of 10 nM streptozotocin): apparent K _m 1.7 mM, apparent K _i 10 nM, and k _cat 440 nkat·kg⁻¹. Compared with non-diabetic control mice, the succinyl-CoA synthetase activity was significantly decreased in the islets and kidneys of mice with early (1 h) and manifest (≧ 2 days) streptozotocin diabetes, whereas the activity in the liver was not significantly altered. Inhibited succinyl-CoA synthetase activity is believed to play a prominent role in the cellular effects of streptozotocin.