SITE-SPECIFIC ISOTOPICALLY-LABELED PROTEINS, AMINO ACIDS, AND BIOCHEMICAL PRECURSORS THEREFOR

摘要

Site-specific isotopically-labeled valine, leucine, and isoleucine andbiosynthetic precursors for these amino acids are provided. Theamino acids are labeled with 13C or 14C at the methyl group carbon atom(s)most remote from the carboxyl group. Also disclosed arethe biochemical precursors of these labeled amino acids, 2-keto-4-(n C)butyricacid and 2-keto-3-(n C-methyl)-4-(n C)-butyric acid inwhich n, at each occurrence, is 13 or 14. Also disclosed are proteins, proteinfragments, and polypeptides containing these site-specificallyisotopically labeled amino acids, and methods for preparing the biochemicalprecursors, the amino acids, and the proteins, protein fragments,and polypeptides.