Patent ID: 7473535

Claim:
A reagent comprising an affinity tag (A), a detectable moiety (D), a linker (L), an isotope tag (T), and a reactive group (R) having the general formula: wherein said reactive group is attached to said isotope tag by a covalent bond, wherein said isotope tag is attached to said linker by a covalent bond, wherein said affinity tag is attached to said linker by a covalent bond, and wherein said detectable moiety is attached to said linker by a covalent bond, wherein said linker links said affinity tag and said detectable moiety to said isotope tag in the configuration shown in said formula, wherein the detectable moiety is radioactive and comprises a radioactive atom selected from the group consisting of 3 H, 14 C, 32 P, 35 S and 125 I.