title: Reaction of osmium reagents with amino acids and proteins. Reactivity of amino acid residues and peptide bond cleavage.
abstract: We report a study of the relative reactivity of the common amino acids and of their residues in lysozyme with osmium tetroxide, the osmium tetroxide-pyridine reagent, and with the oxo-osmium(VI)-pyridine reagent. With free amino acids, the osmium(VIII) reagents are most reactive with Met, Cys, His, Thr, Ser, Trp, Lys, and Pro; the osmium(VI) reagent only reacts significantly with His, Met, Cys, Thr, and Ser. In lysozyme, only Cys, Met, and Trp react extensively with the osmium(VIII) reagents; with the osmium(VI) reagent, Cys and Met are most reactive. We also note evidence both for cross-linking of proteins and for peptide bond cleavage, which appears to have considerable specificity for tryptophanyl residues.
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000378:metabolism*; D009113:Muramidase / Q000378:metabolism*; D009992:Osmium / Q000378:metabolism*; D009993:Osmium Tetroxide / Q000378:metabolism; D011725:Pyridines / Q000378:metabolism
chemical_list: D000596:Amino Acids; D003432:Cross-Linking Reagents; D011725:Pyridines; D009992:Osmium; D009113:Muramidase; D009993:Osmium Tetroxide