A tritium exchange method for characterization of modified histidyl residues and its application to fumarase

✍ Scribed by Gary A. Rogers

• Publisher: Elsevier Science
• Year: 1977
• Tongue: English
• Weight: 242 KB
• Volume: 78
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(77)90101-4

✦ Synopsis

A technique using tritium incorporation into the C-2 position of the imidazolyl ring of histidine for the identification of alkylated histidyl residues is reported. The first-order rate constant for the incorporation of tritium from water into N-methylhistidine (pH S.O,SO"C) is 3.3 x 10~* min-' (tt = 21 min). No other amino acid tested gave more than 0.3% as much incorporation of tritium as did N-methylhistidine. A modified amino acid residue derived from fumarase which had been inactivated by the bifunctional reagent 3,4-bis(bromomethy1) benzoate (I) was conclusively identified as a histidine-I adduct by the above characterization procedure. The technique of measuring tritium incorporation allows the qualitative identification of compounds as histidyl (or imidazolyl) or, alternatively, the quantitative determination of known histidyl compounds, both at picomole levels.