Stable isotope-labeled aromatic amino acids, method for incorporating the same in target protein and method for nmr-structural analysis of proteins

Abstract

The present invention herein provides, for instance, a stable isotope-labeled phenylalanine wherein a carbon atom of the phenyl group linked to an amino acid residue isC, 2 to 4 carbon atoms of the remaining 5 carbon atoms constituting the phenyl group areC atoms to which deuterium atoms are bonded, and the remaining carbon atoms areC atoms to which hydrogen atoms are linked, and a stable isotope-labeled tyrosine wherein a carbon atom of the phenyl group linked to an amino acid residue isC, the carbon atom bonded to the hydroxyl group (OH group) of the phenyl group isC orC, 2 to 4 carbon atoms of the remaining 4 carbon atoms constituting the phenyl group areC atoms to which deuterium atoms are bonded, and the remaining carbon atoms areC atoms to which hydrogen atoms are linked. The stable isotope-labeled amino acid permits the elimination of such a conventional problem concerning the complexity of the NMR signals ascribed to aromatic rings, the complexity being a principal cause of making the NMR analysis difficult, encountered when using the conventional uniformly labeled amino acid residue. Moreover, the isotope-labeled amino acid likewise permits the substantial improvement of the sensitivity thereof to the NMR spectroscopic analysis.