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Synthesis of a bis(aminoethanethiol) ligand with an activated ester group for protein conjugation and 99m Tc labeling
Author(s) -
Eisenhut M.,
Mißfeldt M.,
Lehmann W. D.,
Karas M.
Publication year - 1991
Publication title -
journal of labelled compounds and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0362-4803
DOI - 10.1002/jlcr.2580291204
Subject(s) - chemistry , conjugated system , dithiothreitol , ligand (biochemistry) , hydrolysis , medicinal chemistry , yield (engineering) , covalent bond , reducing agent , desorption , organic chemistry , enzyme , receptor , adsorption , polymer , biochemistry , materials science , metallurgy
The N‐hydroxysuccinimide (NHS) ester of the bis(aminoethanethiol) (BAT) ligand, 6‐(4″‐(4″‐carboxyphenoxy) butyl)‐2, 10‐dimercap‐to‐2, 10‐dimethyl‐4, 8‐diazaundecane, was synthesized by reacting 7‐ (4′‐bromobutyl) ‐3,3, 11, 11‐tetramethyl‐1, 2‐dithia‐5, 9‐diazacycloundecane with the sodium salt of 4‐hydroxybenzoic acid ethyl ester, followed by ester hydrolysis, reductive disulfide cleavage with dithiothreitol (DTT) and activation of the carboxyl group with NHS and dicyclohexylcarbodiimide (DCC). The resulting NHS‐BAT ester was conjugated to monoclonal antibodies at pH 8.5 with about 40% yield. 2–4 BAT ligands conjugated to the antibody did not change the binding characteristics significantly. Proof of the amount of covalent bound BAT ligands was attained by UV‐laser desorption/ionization (UV‐LD/I) mass spectrometry. Complexation with 99m Tc was accomplished by using the tin‐reduction method. The labeling efficiency was >90%.