Regulatory Properties of Perchlorate-extracted Succinate Dehydrogenase

Abstract

Abstract Succinate dehydrogenase extracted from Complex II preparations with 0.8 m sodium perchlorate in the presence of succinate requires no activation (Hanstein, W. G., Davis, K. A., Ghalambor, M. A., and Hatefi, Y. (1971) Biochemistry 10, 2517–2524) even after being subjected to procedures which deactivate other soluble or membranal preparations of the enzyme. This behavior was ascribed to the presence of succinate, a known activator, in the enzyme preparation. In the present study this type of succinate dehydrogenase preparation is shown to contain no bound succinate. The fact that this enzyme requires no activation and does not respond to treatments expected to deactivate it (e.g. dialysis, gel exclusion) has been traced to the effect of high perchlorate concentrations which, in the presence of succinate, appear to alter the regulatory properties. Even at 0°, perchlorate and other anions, in the absence of substrate, activate the dehydrogenase in Complex II, the starting material used for extraction. These ions also activate purified preparations extracted from acetone powders. If succinate is omitted during the contact with perchlorate, the resulting preparations appear to be rapidly and spontaneously deactivated during and following gel exclusion on Sephadex. When succinate is included during perchlorate treatment, however, deactivation is achieved with relative difficulty, using a combination of gel exclusion, exposure to 38°, and prolonged incubation at 0°.