Improved Tritium-Labeling for Quantitative C-Terminal Analysis
The carboxyl-terminal amino acid residues of proteins are selectively tritiated through racemization via the oxazolone intermediate by the action of acetic anhydride in a medium containing 3H2O and pyridine. The characterization of the tritium- labeled C-terminal amino acid, after acid hydrolysis of the tritiated protein, can afford a method for C-terminal analysis [824, 825]. This method has successfully been applied to the qualitative C-terminal determination of proteins [828, 901]. Accumulating data reveals that there still remain several problems to be improved involving reaction conditions or characterization of the tritiated amino acids. The mechanistic features of this reaction are examined below under the improved reaction conditions together with the scope and limitations of this method. Other improvements in the characterization procedure of the radioactive C-terminal amino acid have recently been proposed.
KeywordsAcetic Anhydride Specific Radioactivity Tritiated Water Side Chain Group Amino Acid Amide
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