Premium
Rapid high‐yield N ‐acylation of aminothiols: N ‐acetylglutathione and N ‐acetylhomocysteine and their thiol p K a values
Author(s) -
Shen Biao,
Bazin Cynthia,
English Ann M.
Publication year - 2013
Publication title -
journal of peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 66
eISSN - 1099-1387
pISSN - 1075-2617
DOI - 10.1002/psc.2492
Subject(s) - chemistry , dithiothreitol , reagent , aqueous solution , thiol , acylation , titration , chromatography , yield (engineering) , cationic polymerization , tris , ion exchange , acetylation , cysteine , acetone , nuclear chemistry , organic chemistry , biochemistry , ion , catalysis , materials science , metallurgy , enzyme , gene
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 di N ‐acetylated in ~100% yield in 0.1 M aqueous NaHCO 3 (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, di N ‐acetylGSSG was further purified and desalted on a strong anion‐exchange (SAX) cartridge. Di N ‐acetylhomocystine was simultaneously purified and desalted on a C 18 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 p K a (SH) values of importance for biological studies. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.