REACTION OF OSMIUM REAGENTS WITH AMINO ACIDS AND PROTEINS: Reactivity of Amino Acid Residues and Peptide Bond Cleavage

Publisher Website
Google Scholar
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.