Removal of the 5-nitro-2-pyridine-sulfenyl protecting group from selenocysteine and cysteine by ascorbolysis.

Autor: Ste Marie EJ; Department of Chemistry, Cook Physical Sciences Bldg, University of Vermont, 82 University Place, Burlington, VT, 05405, USA., Ruggles EL; Department of Chemistry, Cook Physical Sciences Bldg, University of Vermont, 82 University Place, Burlington, VT, 05405, USA., Hondal RJ; Department of Biochemistry, University of Vermont, 89 Beaumont Ave., Given Laboratory, Room B413, Burlington, VT, 05405, USA.
Jazyk: angličtina
Zdroj: Journal of peptide science : an official publication of the European Peptide Society [J Pept Sci] 2016 Sep; Vol. 22 (9), pp. 571-6. Date of Electronic Publication: 2016 Aug 02.
DOI: 10.1002/psc.2908
Abstrakt: We previously reported on a method for the facile removal of 4-methoxybenzyl and acetamidomethyl protecting groups from cysteine (Cys) and selenocysteine (Sec) using 2,2'-dithiobis-5-nitropyridine dissolved in trifluoroacetic acid, with or without thioanisole. The use of this reaction mixture removes the protecting group and replaces it with a 2-thio(5-nitropyridyl) (5-Npys) group. This results in either a mixed selenosulfide bond or disulfide bond (depending on the use of Sec or Cys), which can subsequently be reduced by thiolysis. A major disadvantage of thiolysis is that excess thiol must be used to drive the reaction to completion and then removed before using the Cys-containing or Sec-containing peptide in further applications. Here, we report a further advancement of this method as we have found that ascorbate at pH 4.5 and 25 °C will reduce the selenosulfide to the selenol. Ascorbolysis of the mixed disulfide between Cys and 5-Npys is much less efficient but can be accomplished at higher concentrations of ascorbate at pH 7 and 37 °C with extended reaction times. We envision that our improved method will allow for in situ reactions with alkylating agents and electrophiles without the need for further purification, as well as a number of other applications. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.
(Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.)
Databáze: MEDLINE
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