Enzyme-mediated site-specific bioconjugation of metal complexes to proteins: sortase-mediated coupling of copper-64 to a single-chain antibody.
The enzyme-mediated site-specific bioconjugation of a radioactive metal complex to a single-chain antibody using the transpeptidase sortase A is reported. Cage amine sarcophagine ligands that were designed to function as substrates for the sortase A mediated bioconjugation to antibodies were synthesized and enzymatically conjugated to a single-chain variable fragment. The antibody fragment scFv(anti-LIBS) targets ligand-induced binding sites (LIBS) on the glycoprotein receptor GPIIb/IIIa, which is present on activated platelets. The immunoconjugates were radiolabeled with the positron-emitting isotope (64)Cu. The new radiolabeled conjugates were shown to bind selectively to activated platelets. The diagnostic potential of the most promising conjugate was demonstrated in an in vivo model of carotid artery thrombosis using positron emission tomography. This approach gives homogeneous products through site-specific enzyme-mediated conjugation and should be broadly applicable to other metal complexes and proteins.
School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Vic (Australia).
Brett M
BM
Paterson
Karen
K
Alt
Charmaine M
CM
Jeffery
Roger I
RI
Price
Shweta
S
Jagdale
Sheena
S
Rigby
Charlotte C
CC
Williams
Karlheinz
K
Peter
Christoph E
CE
Hagemeyer
Paul S
PS
Donnelly
D019881:Aminoacyltransferases / Q000737:chemistry*; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D003546:Cysteine Endopeptidases / Q000737:chemistry*; D051379:Mice; D015394:Molecular Structure; D057127:Single-Chain Antibodies / Q000737:chemistry*
D001426:Bacterial Proteins; D056831:Coordination Complexes; D057127:Single-Chain Antibodies; D003300:Copper; D019881:Aminoacyltransferases; C120542:sortase A; D003546:Cysteine Endopeptidases
bioconjugation; bioinorganic chemistry; copper; macrocyclic ligands; radiopharmaceuticals