title: Fluorescence studies on the interaction between two cytochromes extracted from the yeast, Hansenula anomala.
abstract: The binding of cytochrome c to the cytochrome b2 core, both extracted from the yeast, Hansenula anomala, has been studied. Cytochrome b2 core heme is extracted and replaced by the fluorescent probe, 2-p-toluidinylnaphthalene-6-sulfonate (TNS). A dissociation constant in the range of 85 microM is found for the TNS-apoprotein complex with a stoichiometry of 1:1. The interaction between the two proteins is followed by monitoring changes in the TNS fluorescence. We find the interaction between the cytochrome c and the apocytochrome b2 core to be dependent upon the ionic strength. The dissociation constant of this complex at 20 mM ionic strength is 6 +/- 2 microM with a 1:1 stoichiometry. This dissociation constant is similar to that estimated, by other researchers, for the dimer Zn cytochrome c-cytochrome b2 core complex.
mesh_terms: D003574:Cytochrome c Group / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D042844:L-Lactate Dehydrogenase (Cytochrome); D008433:Mathematics; D009282:Naphthalenesulfonates; D009994:Osmolar Concentration; D010843:Pichia / Q000201:enzymology*; D004718:Saccharomycetales / Q000201:enzymology*; D013050:Spectrometry, Fluorescence
chemical_list: D003574:Cytochrome c Group; D009282:Naphthalenesulfonates; C009497:2-(4-toluidino)-6-naphthalenesulfonic acid; D007770:L-Lactate Dehydrogenase; D042844:L-Lactate Dehydrogenase (Cytochrome)