title: Biodistribution and catabolism of 18F-labelled isopeptide N(epsilon)-(gamma-glutamyl)-L-lysine.
abstract: Isopeptide bonds between the epsilon-amino group of lysine and the gamma-carboxamide group of glutamine are formed during strong heating of pure proteins or, more important, by enzymatic reaction mediated by transglutaminases. Despite the wide use of a microbial transglutaminase in food biotechnology, up to now little is known about the metabolic fate of the isopeptide N(epsilon)-(gamma-glutamyl)-L-lysine. In the present study, N-succinimidyl-4-[(18)F]fluorobenzoate was used to modify N(epsilon)-(gamma-glutamyl)-L-lysine at each of its two alpha-amino groups, resulting in the 4-[(18)F]fluorobenzoylated derivatives, for which biodistribution, catabolism, and elimination were investigated in male Wistar rats. A significant different biochemical behavior of the two labelled isopeptides was observed in terms of in vitro stability, in vivo metabolism as well as biodistribution. The results suggest that the metabolic fate of isopeptides is likely to be dependent on how they are reabsorbed - free or peptide bound.
authors.affiliation: Positron Emission Tomography Center, Institute of Bioinorganic and Radiopharmaceutical Chemistry, Research Center Rossendorf, Dresden, Germany. ch.hultsch@fz-rossendorf.de
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: Pawelke
authors.forename: J
authors.initials: J
authors.lastname: Pietzsch
authors.forename: F
authors.initials: F
authors.lastname: Wuest
authors.forename: B
authors.initials: B
authors.lastname: Johannsen
authors.forename: T
authors.initials: T
authors.lastname: Henle
mesh_terms: D000818:Animals; D004151:Dipeptides / Q000737:chemistry / Q000378:metabolism* / Q000493:pharmacokinetics*; D005462:Fluorine Radioisotopes; D066298:In Vitro Techniques; D007553:Isotope Labeling / Q000379:methods; D008297:Male; D015394:Molecular Structure; D049268:Positron-Emission Tomography / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D012680:Sensitivity and Specificity
chemical_list: D004151:Dipeptides; D005462:Fluorine Radioisotopes; C001299:epsilon-(gamma-glutamyl)-lysine