title: Cysteine residues as catalysts for covalent peptide and protein modification: a role for thiyl radicals?
abstract: Cysteine thiyl radicals engage in reversible intramolecular hydrogen-transfer reactions with amino acid residues in peptides and proteins. These reactions can be experimentally demonstrated through covalent hydrogen-deuterium exchange when experiments are carried out in (2)H2O. To this end, hydrogen-transfer reactions have been observed between cysteine thiyl radicals and glycine, alanine, serine, valine and leucine in both model peptides and a protein, insulin. The relevance of such reactions for protein oxidation under conditions of oxidative stress is discussed.
authors.affiliation: Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS 66047, USA. schoneic@ku.edu
authors.forename: Christian
authors.initials: C
authors.lastname: Schöneich
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D003545:Cysteine / Q000737:chemistry*; D041961:Deuterium Exchange Measurement / Q000379:methods; D005609:Free Radicals / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D007328:Insulin / Q000737:chemistry / Q000378:metabolism; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D005609:Free Radicals; D007328:Insulin; D010455:Peptides; D013438:Sulfhydryl Compounds; D002244:Carbon; D006859:Hydrogen; D003545:Cysteine