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Enzyme‐Mediated Site‐Specific Bioconjugation of Metal Complexes to Proteins: Sortase‐Mediated Coupling of Copper‐64 to a Single‐Chain Antibody |
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| Authors: | Dr. Brett M. Paterson Dr. Karen Alt Charmaine M. Jeffery Prof. Roger I. Price Shweta Jagdale Dr. Sheena Rigby Dr. Charlotte C. Williams Prof. Karlheinz Peter Prof. Christoph E. Hagemeyer Assoc. Prof. Paul S. Donnelly |
| Affiliation: | 1. School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Vic (Australia);2. Vascular Biotechnology (K.A., C.E.H., S.J.), Atherothrombosis and Vascular Biology (K.?A., K.P., S.R.), Baker IDI Heart and Diabetes Institute, Melbourne, Vic (Australia);3. Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Nedlands, WA (Australia);4. School of Physics, The University of Western Australia, Nedlands, WA (Australia);5. CSIRO Materials Science and Engineering, 343 Royal Parade, Melbourne, VIC (Australia);6. Central Clinical School, Monash University, Melbourne (Australia) |
| Abstract: | 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 scFvanti‐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 64Cu. 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. |
| Keywords: | bioconjugation bioinorganic chemistry copper macrocyclic ligands radiopharmaceuticals |