Mitochondrial rhodanese: membrane-bound and complexed activity.

We have proposed that phosphorylated and dephosphorylated forms of the mitochondrial sulfurtransferase, rhodanese, function as converter enzymes that interact with membrane-bound iron-sulfur centers of the electron transport chain to modulate the rate of mitochondrial respiration (Ogata, K., Dai, X., and Volini, M.

Bovine mitochondrial rhodanese is a phosphoprotein.

The mitochondrial sulfurtransferase, rhodanese, has been analyzed for phosphate content. Significant amounts of protein-bound phosphate (30-40%) were measured in the six rhodanese preparations examined. Chromatographic experiments followed by phosphate analyses done on two of the preparations indicated that rhodanese A and rhodanese B, two enzyme forms that were previously resolved on DEAE-Sephadex by Blumenthal and Heinrikson (Blumenthal, K.

Properties of an Escherichia coli rhodanese.

A rhodanese enzyme of less than 20,000 molecular weight has been purified from Escherichia coli. The enzyme is accessible to substrates upon addition of whole cells to standard assay mixtures. This rhodanese has a Stokes radius of 17 A which for a globular protein corresponds to a molecular weight close to 14,000.

The different molecular weight forms of bovine liver rhodanese.

Sedimentation equilibrium studies show that there are two forms of bovine liver rhodanese in crystalline enzyme preparations of full specific activity. One form dissociates to a species with a limiting molecular weight close to 19,000. The second form is nondissociable under the same experimental conditions.