| 摘要 |
Site-specific isotopically-labeled valine, leucine, and isoleucine and biosynthetic precursors for these amino acids are provided. The amino acids are labeled with <13>C or <14>C at the methyl group carbon atom(s) most remote from the carboxyl group. Also disclosed are the biochemical precursors of these labeled amino acids, 2-keto-4-(<n>C)butyric acid and 2-keto-3-(<n>C-methyl)-4-(<n>C)-butyric acid in which n, at each occurrence, is 13 or 14. Also disclosed are proteins, protein fragments, and polypeptides containing these site-specifically isotopically labeled amino acids, and methods for preparing the biochemical precursors, the amino acids, and the proteins, protein fragments, and polypeptides. |
