title: Radiolabelling of isopeptide N epsilon-(gamma-glutamyl)-L-lysine by conjugation with N-succinimidyl-4-[18F]fluorobenzoate.
abstract: The isopeptide N(epsilon)-(gamma-glutamyl)-L-lysine 4 was labelled with 18F via N-succinimidyl-4-[18F]fluorobenzoate ([18F]SFB). A modified approach for the convenient synthesis of [18F]SFB was used, and [18F]SFB could be obtained in decay-corrected radiochemical yields of 44-53% (n = 20) and radiochemical purity >95% within 40 min after EOB. For labelling N(epsilon)-(gamma-glutamyl)-L-lysine with [18F]SFB the effects of isopeptide concentration, temperature, and pH were studied to determine the optimum reaction conditions. The coupling reaction was shown to be temperature and pH independent while being strongly affected by the isopeptide concentration. Using the optimized labelling conditions, in a typical experiment 1.3GBq of [18F]SFB could be converted into 447MBq (46%, decay-corrected) of [18F]fluorobenzoylated isopeptide within 45 min, including HPLC purification.
authors.affiliation: Institut für Bioanorganische und Radiopharmazeutische Chemie, FZ-Rossendorf e.V., PF 51 01 19, Dresden 01314, Germany. f.wuest@fz-rossendorf.de
authors.forename: F
authors.initials: F
authors.lastname: Wüst
authors.forename: C
authors.initials: C
authors.lastname: Hultsch
authors.forename: R
authors.initials: R
authors.lastname: Bergmann
authors.forename: B
authors.initials: B
authors.lastname: Johannsen
authors.forename: T
authors.initials: T
authors.lastname: Henle
mesh_terms: D001565:Benzoates / Q000737:chemistry* / Q000302:isolation & purification; D015415:Biomarkers / Q000737:chemistry; D004151:Dipeptides / Q000032:analysis / Q000737:chemistry*; D005462:Fluorine Radioisotopes; D006863:Hydrogen-Ion Concentration; D007553:Isotope Labeling / Q000379:methods; D011851:Radioactivity; D011854:Radiochemistry; D013237:Stereoisomerism; D013388:Succinimides / Q000737:chemistry* / Q000302:isolation & purification; D013696:Temperature
chemical_list: D001565:Benzoates; D015415:Biomarkers; D004151:Dipeptides; D005462:Fluorine Radioisotopes; D013388:Succinimides; C075713:N-succinimidyl-4-fluorobenzoate; C001299:epsilon-(gamma-glutamyl)-lysine