Mitochondrial and cytosolic rhodanese from liver of DAB treated mice. II. Some properties and spectral studies.

Rhodanese (thiosulfate: cyanide sulfurtransferase) shows distinctive mitochondrial and cytoplasmic activities in several models of tumorigenesis. To investigate the basis for these differences, the enzyme was purified from the mitochondrial and cytosolic liver fractions of mice treated with the carcinogen p-dimethyl-aminoazobenzene (DAB) and some properties were studied. Mitochondrial and cytoplasmic rhodanese exhibited different responses to the effect of ionic strength, denaturants, sulphydryl reagents, lipids and detergents, but no significant difference between enzymes purified from controls or DAB treated animals was observed. It is important to note that although chemical studies did not show very striking differences between either of the rhodanese forms, fluorescence spectral studies suggested that in DAB-treated mice, the cytosolic rhodanese would be present almost completely as the sulfur-free form, while the mitochondrial enzyme would be present as the sulfur-substituted form. These findings would justify the high rhodanese activity present in mitochondria. On the other hand, in control animals, rhodanese would exist only as the partial sulfur-substituted form in both fractions.