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Straightforward thiol-mediated protein labelling with DTPA: Synthesis of a highly active 111In-annexin A5-DTPA tracer

Authors
  • Kratz, Harald1
  • Haeckel, Akvile1
  • Michel, Roger1
  • Schönzart, Lena1
  • Hanisch, Uli2
  • Hamm, Bernd1
  • Schellenberger, Eyk1
  • 1 Charité - Universitätsmedizin Berlin, Department of Radiology, Charitéplatz 1, Berlin, 10117, Germany , Berlin (Germany)
  • 2 AnaKat – Institut für Biotechnologie GmbH, Robert-Koch-Platz 4, Berlin, 10115, Germany , Berlin (Germany)
Type
Published Article
Journal
EJNMMI Research
Publisher
Springer (Biomed Central Ltd.)
Publication Date
Apr 27, 2012
Volume
2
Issue
1
Identifiers
DOI: 10.1186/2191-219X-2-17
Source
Springer Nature
Keywords
License
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Abstract

BackgroundAnnexin A5 (anxA5) has been found useful for molecular imaging of apoptosis and other biological processes.MethodsHere, we report an optimised two-step synthesis of annexin A5-diethylene triamine pentaacetic acid (DTPA) (anxA5-DTPA) for positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging with a single purification step. The use of a recombinant annexin A5 (cys-anxA5) with a single thiol group allowed regionally specific coupling, without affecting the binding domain of cys-anxA5.ResultsThe metal complexing capacity of anxA5-DTPA was investigated by labelling with 111In3+ and Eu3+. Binding of modified anxA5-DTPA to apoptotic cells was tested in competition experiments with a fluorescent anxA5 derivative (anxA5-FITC) using flow cytometry and compared with that of wildtype anxA5 or non-binding anxA5-DTPA (M1234-anxA5-DTPA). The binding affinity to apoptotic cells of the anxA5-DTPA conjugate does not differ from that of wildtype anxA5.ConclusionsThis two-step synthesis of annexin A5-DTPA resulted in biologically active anxA5-DTPA, which can be labelled with radionuclides for use in SPECT and PET imaging.

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