Patent ID: 8022173

Claim:
A composition of stable isotope-labeled amino acids wherein all of the aliphatic amino acids constituting a target protein satisfy the following requirements concerning the labeling pattern: (a) When only one methylene group carrying two hydrogen atoms exists, one of the methylene hydrogen atoms is deuterated; (b) When at least two methylene groups each carrying two hydrogen atoms exist, one of the methylene hydrogen atoms of at least one of the methylene groups is deuterated and the both of the two methylene hydrogen atoms of at least one of the methylene groups are likewise deuterated; (c) When pro-chiral gem-methyl groups exist, all of the hydrogen atoms on one of the methyl groups are completely deuterated while the hydrogen atoms on the other methyl groups are partially deuterated; (d) When a further methyl group in addition to the foregoing ones exists, the methyl group is partially deuterated, or the methyl group is completely deuterated; and (e) side chain methine hydrogen atoms are deuterated; wherein the aliphatic amino acids are selected from the group consisting of arginine, glutamine, glutamic acid, isoleucine, leucine, lysine, methionine, proline, threonine and valine; and wherein the isotope is selected from carbon, hydrogen, and nitrogen.