Influence of pH and flanking serine on the redox potential of S-S and S-Se bridges of Cys-Cys and Cys-Sec peptides.
In selenocysteine (Sec, U)-containing proteins the selenenylsulfide bridge and its reduced thiol-selenol counterpart are usually the significant species. An important role for serine as flanking amino acid in the redox potential of S-S and S-Se bridges was proposed for some thioredoxin reductases. To check the generality of this proposal, model tetrapeptides (GCCG, SCCG, GCCS, SCCS, GCUG, SCUG, GCUS, SCUS) were synthesized, including the GCUG sequence of human thioredoxin reductase. The influence on the redox potential of S-Se and S-S bridges as a function of pH and of serine at different positions reveals (i) a strong general pH dependence, and (ii) a significant influence of flanking serine on disulfide only at basic pH.
Schneider
Alex
A
Leibniz Institute of Plant Biochemistry, Department of Bioorganic Chemistry, Weinberg 3, D-06120 Halle/Saale, Germany.
Brandt
Wolfgang
W
Wessjohann
Ludger A
LA
D003545:Cysteine / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D012643:Selenium / Q000737:chemistry; D017279:Selenocysteine / Q000737:chemistry*; D012694:Serine / Q000737:chemistry*
D004220:Disulfides; D010455:Peptides; D017279:Selenocysteine; D012694:Serine; D012643:Selenium; D003545:Cysteine