Patent ID: 7132295

Claim:
An organic compound of the formula (II), in which the groups A, PRG, S, Z, L′, Z′ and k, l, m and n, are defined as follows: A is the acyl residue of an affinity ligand selected from biotinyl and a biotin derivative, or is a functional group which is bound to a polymeric support, and is a support-bound hydroxyl, carboxyl or amino group, PRG is the residue of a protein-reactive group, selected from —CO—(CH 2 ) r —Cl in which r=1–10, and —CO—CH═CH 2 ; S is an acid-cleavable group of the formula in which Y is a spacer selected from NH, NH—CH 2 , NH—CH 2 —CH 2 —NH—CO and CH 2 —CO, where Y can be in the ortho, meta or para position in relation to NH, and in which SK is the side chain residue of an α-amino acid of the formula SK—CH(NH 2 )—COOH selected form the side chains of the 20 natural amino acids, which, in the case of SKs other than an H atom, can be present in the D, L or racemic from, Z is the residue of an amino acid, which is not labeled or which can contain 13 C or 15 N labels, or a combination of these labels, selected from the 20 natural proteinogenic amino acids, and residues of ω-amino acids, selected from NH—(CH 2 ) 2 —CO and CO—(CH 2 ) 2 —NH, which, where appropriate, can be in the D, L or racemic form, L′ is a bridge which makes possible, or facilitates, the covalent linkage of two piperazine residues, which can, where appropriate, contain 13 C or 15 N isotope labels or a combination of these labels, selected from CO—CO, CO—(CH 2 ) s —CO and also CO-arylene-CO, CO—CH 2 —NH—CO—NH—CH 2 —CO, CO—NH—CH 2 —CO, CO—CH 2 —NH—CO, CO—CH 2 —NH—CO—CO—NH—CH 2 —CO, CO—CH 2 —NH—CO—(CH 2 ) s —CO—NH—CH 2 —CO, CO—CH 2 —NH—CO-arylene-CO—NH—CH 2 —CO, (CH 2 ) s —NH—CO—CO—NH—(CH 2 ) s , (CH 2 ) 3 —NH—CO—CO—NH—(CH 2 ) 3 , (CH 2 ) s —CO, (CH 2 ) 2 —CO, CO and CS, where s is an integer between 1 and 6, R and R′ are hydrogen, Z′ is the residue of an amino acid, which differs from Z in the different orientation in regard to the terminal CO and NH groups; it may not be labeled or may contain 13 C or 15 N labels, or a combination of these labels selected from the 20 natural proteinogenic amino acids, and residues of ω-amino acids, selected from NH—(CH 2 ) 2 —CO and CO—(CH 2 ) 2 —NH, which, where appropriate, can be in the D, L or racemic form, k, l, m and n can, independently of each other, in each case be numbers between 0 and 10, where the sum of k+l+m+n is greater than 0 and less than 20, with the proviso that at least one of Z, L′, and Z′ is labeled with 13 C and/or 15 N; or a pharmaceutically acceptable salt thereof.