Abstract
Succinate dehydrogenase has been solubilized from R. rubrum chromatophores with the use of chaotropic agents, and purified approximately 80-fold. The preparation (SD r) contains 8 g-atoms of iron per mole of flavin, and has a turnover number of approximately 4000 (moles succinate oxidized by ferricyanide or phenazine methosulfate/mole of flavin/min at 38 °C). Its absorption and EPR spectra are similar to those of bovine heart succinate dehydrogenase. SD r can cross-interact with the bovine heart electron-transport system (alkali-inactivated ETP) and reconstitute succinoxidase activity with an efficiency comparable to the reconstitution activity of purified bovine heart succinate dehydrogenase. Preliminary results suggest that SD r has a molecular weight of approximately 85,000, and that it is composed of a flavoprotein subunit with a molecular weight of approximately 60,000, plus a second subunit (possibly an iron-sulfur protein) with a molecular weight of approximately 25,000.
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