title: Reaction of S-(2-amino-2-carboxyethylsulfonyl)-L-cysteine with thiosulfate: synthesis of L-alanine sulfodisulfane and application to the determination of thiosulfate.
abstract: A new reaction of S-(2-amino-2-carboxyethylsulfonyl)-L-cysteine (ACESC) with thiosulfate is described. The reaction proceeded quantitatively in formic or acetic acid solutions, yielding equimolar amounts of L-alanine sulfodisulfane (2-amino-2-carboxyethyl sulfodisulfane) and L-alanine 3-sulfinic acid. L-Alanine sulfodisulfane was obtained as pure monosodium salt; the yield was 92% of the theoretical. A new method is described for the determination of thiosulfate. The method is based on the quantitative reaction between ACESC and thiosulfate, and L-alanine sulfodisulfane, one of the reaction products, was determined using acid ninhydrin reagent 2 of M. K. Gaitonde (1967, Biochem. J. 104, 627-633). The recovery was over 95%. When samples contained sulfite in addition to thiosulfate, S-sulfo-L-cysteine (T. Ubuka et al., 1982, Anal. Biochem. 126, 273-277) was produced in addition to L-alanine sulfodisulfane by the treatment with ACESC. Both products were separated by a small Dowex 1 column and determined with the acid ninhydrin reagent 2. The recoveries were over 95%. The new method was applied to the thiosulfate sulfurtransferase reaction, in which thiosulfate, a substrate, and sulfite, a product, were determined separately.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D002852:Chromatography, Ion Exchange; D003545:Cysteine / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D013055:Spectrophotometry, Infrared; D013447:Sulfites / Q000032:analysis; D013884:Thiosulfate Sulfurtransferase; D013885:Thiosulfates / Q000032:analysis*
chemical_list: D013447:Sulfites; D013885:Thiosulfates; C036162:cysteine thiosulfonate; C036581:cystine disulfoxide; D013884:Thiosulfate Sulfurtransferase; D003545:Cysteine