Patent ID: 7022310

Claim:
A combination of stable isotope-labeled amino acids constituting a target protein, wherein all amino acids constituting the target protein have the following label patterns: (a) when a methylene group having two hydrogen atoms is present, one methylene hydrogen atom is deuterated, (b) when prochiral gem-methyl groups are present, all hydrogen atoms in one methyl group are completely deuterated and hydrogen atoms in the other methyl group are partially deuterated, (c) when a methyl group other than those stated above in (b) is present, then all hydrogen atoms except one of them in the methyl group are deuterated or all hydrogen atoms in the methyl group are deuterated, (d) when the aromatic ring has hydrogen atoms, the hydrogen atoms in the aromatic ring may be partially deuterated, (e) after the deuteration in above (a), (b), and (c), all carbon atoms of hydrogen atom-containing methylene group and/or methyl group are replaced with 13 C, and (f) all nitrogen atoms are replaced with 15 N.