Premium
Synthesis of selenocysteine peptides and their oxidation to diselenide‐bridged compounds
Author(s) -
Besse Dörthe,
Moroder Luis
Publication year - 1997
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/(sici)1099-1387(199711)3:6<442::aid-psc122>3.0.co;2-2
Subject(s) - selenocysteine , chemistry , diselenide , selenium , trifluoroacetic acid , diphenyl diselenide , peptide , bovine pancreatic ribonuclease , selenide , cystamine , epimer , cysteine , stereochemistry , combinatorial chemistry , medicinal chemistry , organic chemistry , ribonuclease , biochemistry , rna , enzyme , gene
Using the Fmoc/tBu protection scheme and the p ‐methoxybenzyl derivative of selenocysteine, the synthesis of related peptides in the selenol‐protected form could be optimized by operating the coupling steps in the absence of auxiliary bases and by reducing the piperidine treatment to the minimum time required for quantitative Fmoc cleavage. Under these conditions, β‐elimination of the p ‐methoxybenzylselenol as the main side reaction of these syntheses, as well as epimerization of the protected selenocysteine, was largely suppressed. Conversion of the selenol‐ and thiol‐protected bis‐selenocysteine and selenocysteine, cysteine peptides into the related cyclic monomeric forms by iodine‐mediated oxidation failed since a complex mixture of compounds was produced. Cleavage of the selenoether bond with mercuric acetate was found to proceed smoothly, but displacement of the heavy metal ions by treatment with excesses of thiols or hydrogen sulphide was unsuccessful since a stable Hg 2+ diselenide complex was obtained. However, oxidation was achieved in good yields by the dimethylsulphoxide/trifluoroacetic acid procedure and the peptides were then used for determining the redox potential of the diselenide and selenide/sulphide bridge, respectively. © 1997 European Peptide Society and John Wiley & Sons, Ltd.