MITOCHONDRIAL AND CYTOSOLIC RHODANESE FROM LIVER OF DAB TREATED MICE .2. SOME PROPERTIES AND SPECTRAL STUDIES

Rhodanese (thiosulfate: cyanide sulfurtransferase) shows distinctive m itochondrial and cytoplasmic activities in several models of tumorigen esis. To investigate the basis for these differences, the enzyme was p urified from the mitochondrial and cytosolic liver fractions of mice t reated with the carcinogen p-dimethyl-aminoazobenzene (DAB) and some p roperties were studied. Mitochondrial and cytoplasmic rhodanese exhibi ted different responses to the effect of ionic strength, denaturants, sulphydryl reagents, lipids and detergents, but no significant differe nce between enzymes purified from controls or DAB treated animals was observed. rt is important to note that although chemical studies did n ot show very striking differences between either of the rhodanese form s, fluorescence spectral studies suggested that in DAB-treated mice, t he cytosolic rhodanese would be present almost completely as the sulfu r-free form, while the mitochondrial enzyme would be present as the su lfur-substituted form. These findings would justify the high rhodanese activity present in mitochondria. On the other hand, in control anima ls, rhodanese would exist only as the partial sulfur-substituted form in both fractions.