Production of [F-18]Fluoroannexin for Imaging Apoptosis with PET

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Recombinant human-annexin-V was conjugated with 4-[F-18]fluorobenzoic acid (FBA) via its reaction with the N-hydroxysuccinimidyl ester (FBA-OSu) at pH 8.5. A series of reactions using varying amounts of annexin-V, unlabeled FBA-OSu, and time produced products with different conjugation levels. Products were characterized by mass spectrometry and a cell-binding assay to assess the effect of conjugation. In each case, the conjugated protein was a mixture of proteins with a range of conjugation. Annexin-V could be conjugated with an average of two FBA mole equivalents without decreasing its affinity for red blood cells (Kd 6-10 μM) with exposed phosphatidylserine. An average conjugation of 7.7 (range 3-13) diminished the binding 3-fold. Large-scale production and purification of [F-18]-FBA-OSu from [F-18] fluoride was accomplished within 90 min and in 77% radiochemical yield (decay-corrected to the end of cyclotron bombardment). The conjugation reaction of annexin with [F-18]FBA-OSu was studied with respect to activity level, protein mass, and concentration. Under the most favorable conditions, >25 mCi [F-18]fluoroannexin (FAN) was isolated in 64% yield (decay-corrected for a 22 min conjugation process) from labeling 1.1 mg of annexin-V. A pilot PET imaging study of [F-18]fluoroannexin in normal rats showed high uptake in the renal excretory system and demonstrated sufficient clearance from most other internal organs within 1 h. [F-18]Fluoroannexin should prove useful in imaging targeted apoptosis.

Original languageEnglish (US)
Pages (from-to)373-379
Number of pages7
JournalBioconjugate Chemistry
Issue number2
Publication statusPublished - Mar 2004
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Organic Chemistry
  • Clinical Biochemistry
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry

Cite this

Grierson, J. R., Yagle, K. J., Eary, J. F., Tait, J. F., Gibson, D. F., Lewellen, B., ... Krohnt, K. A. (2004). Production of [F-18]Fluoroannexin for Imaging Apoptosis with PET. Bioconjugate Chemistry, 15(2), 373-379.