title: Rapid high-yield N-acylation of aminothiols: N-acetylglutathione and N-acetylhomocysteine and their thiol pK(a) values.
abstract: Methodology for the rapid N-acylation of aminothiols in aqueous solution using procedures commonly employed in biochemical studies is described here. Glutathione disulfide (GSSG) and homocystine were diN-acetylated in ~100% yield in 0.1 M aqueous NaHCO3 (pH 8.5) at room temperature by 2.5 equiv of the activated ester, N-hydroxysulfosuccinimidyl acetate, an efficient water-soluble acetylating reagent. Following acetone precipitation, diN-acetylGSSG was further purified and desalted on a strong anion-exchange (SAX) cartridge. DiN-acetylhomocystine was simultaneously purified and desalted on a C18 cartridge. The N-acetylated aminothiols were generated using gel-immobilized tris(2-carboxyethyl)phosphine as a reductant, which obviated the need for further purification. Alternatively, disulfide exchange with dissolved dithiothreitol yielded N-acetylglutathione, which was purified on the SAX cartridge. pH titrations of N-acetylglutathione (8.99) and N-acetylhomocysteine (9.66) as well as those of commercially available N-acetylcysteine (9.53) and N-acetylpenicillamine (10.21) yielded pK(a) (SH) values of importance for biological studies.
authors.affiliation: Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec H4B 1R6, Canada.
authors.forename: Biao
authors.initials: B
authors.lastname: Shen
authors.forename: Cynthia
authors.initials: C
authors.lastname: Bazin
authors.forename: Ann M
authors.initials: AM
authors.lastname: English
mesh_terms: D000215:Acylation; D004229:Dithiothreitol / Q000737:chemistry; D005978:Glutathione / Q000031:analogs & derivatives* / Q000737:chemistry; D019803:Glutathione Disulfide / Q000737:chemistry; D006710:Homocysteine / Q000031:analogs & derivatives* / Q000737:chemistry; D006711:Homocystine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D012996:Solutions / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D012996:Solutions; D013438:Sulfhydryl Compounds; D014867:Water; D006710:Homocysteine; C084569:N-acetylglutathione; D006711:Homocystine; C025584:N-acetylhomocysteine; D005978:Glutathione; D004229:Dithiothreitol; D019803:Glutathione Disulfide