Site-specific labeling of annexin V with F-18 for apoptosis imaging

Xuehe Li, Jeanne M. Link, Svetlana Stekhova, Kevin J. Yagle, Christina Smith, Kenneth A. Krohn, Jonathan F. Tait

Research output: Contribution to journalArticle

81 Scopus citations

Abstract

Annexin V is useful in detecting apoptotic cells by binding to phosphatidylserine (PS) that is exposed on the outer surface of the cell membrane during apoptosis. In this study, we examined the labeling of annexin V-128, a mutated form of annexin V that has a single cysteine residue at the NH2 terminus, with the thiol-selective reagent 18F- labeling agent N-[4-[(4-[18F]fluorobenzylidene)aminooxy]butyl] maleimide ([18F]FBABM). We also examined the cell binding affinity of the 18F-labeled annexin V-128 ([18F]FAN-128). [ 18F]FBABM was synthesized in two-step, one-pot method modified from literature procedure. (Toyokuni et al., Bioconjugate Chem. 2003, 14, 1253-1259). The average yield of [18F]FBABM was 23 ± 4% (n = 4, decay-corrected) and the specific activity was ∼6000 Ci/mmol. The total synthesis time was ∼92 min. The critical improvement of this study was identifying and then developing a purification method to remove an impurity N-[4-[(4-dimethylaminobenzylidene)aminooxy]butyl]maleimide 4, whose presence dramatically decreased the yield of protein labeling. Conjugation of [ 18F]FBABM with the thiol-containing annexin V-128 gave [ 18F]FAN-128 in 37 ± 9% yield (n = 4, decay corrected). Erythrocyte binding assay of [18F]FAN-128 showed that this modification of annexin V-128 did not compromise its membrane binding affinity. Thus, an in vivo investigation of [18F]FAN-128 as an apoptosis imaging agent is warranted.

Original languageEnglish (US)
Pages (from-to)1684-1688
Number of pages5
JournalBioconjugate Chemistry
Volume19
Issue number8
DOIs
StatePublished - Aug 1 2008

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Biomedical Engineering
  • Pharmacology
  • Pharmaceutical Science
  • Organic Chemistry

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