The effects of carbodiimides on functions associated with the energy-conservation mechanism in beef heart sub-mitochondrial particles

N,N'-di-n-propyl-, N,N'di-n-butyl-, N,N'-di-n-pentyl-, N,N'di-n-hexyl-, N,N'di-n-octoyl, N,N'-dibenzhydryl-, and N,N'-dibenzhydrylcarbodiimides were synthesized. They were all effective inhibitors (2 nmoles carbodiimide per milligram protein) of the ATP-driven reduction of NAD by succinate and the ATP-driven transhydrogenase activities catalyzed by beef heart submitochondrial particles (SMP). They had no effect on the nonenergy-linked transhydrogenase and stimulated the succinate-driven aerobic transhydrogenase activity of beef heart SMP. It was concluded that they exert their effects by reacting with the N,N'-dicyclohexylcarbodiimide-binding protein. Water-soluble carbodiimides were not effective inhibitors.