title: Euglena gracilis cadmium-binding protein-II contains sulfide ion.
abstract: Sulfide ions are a constituent of the cadmium-binding protein-II in the alga Euglena gracilis. Their presence was demonstrated by the methylene blue assay, by acid labilization induced reductions in the Cd-S charge transfer band at 254 nm and by reactions with the thiol reagent, 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB). Direct reduction of DTNB by sulfide and precipitation of CdS yield a complex stoichiometry for the DTNB reaction. The S2-/Cd2+ ratios determined, 1.25 +/- 0.10 (methylene blue) and 1.37 +/- 0.16 (DTNB), are in good agreement.
mesh_terms: D000818:Animals; D011232:Chemical Precipitation; D004228:Dithionitrobenzoic Acid; D005056:Euglena gracilis / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D008668:Metallothionein / Q000032:analysis*; D008751:Methylene Blue; D010084:Oxidation-Reduction; D013053:Spectrophotometry; D013440:Sulfides / Q000032:analysis*
chemical_list: D013440:Sulfides; C004203:cadmium-binding protein; D008668:Metallothionein; D004228:Dithionitrobenzoic Acid; D008751:Methylene Blue