| abstract |
Seat-specific isotopically labeled valine, leucine and isoleucine. and biosynthetic precursors for these amino acids are described. The amino acids are labeled with C or C at the methyl group carbon atom or atoms furthest away from the carboxyl group. Also described are the biochemical precursors of these labeled amino acids, 2-keto-4- (nC) -butyric acid and 2-keto - (- methyl) -4 - () - butyric acid, where n, each time it occurs, Also described are proteins, protein fragments and polypeptides containing these site-specific isotopically labeled amino acids, and methods of making the biochemical precursors, amino acids and proteins, protein fragments and polypeptides. |