title: Hexa-histidine tag as a novel alternative for one-step direct labelling of a single-chain Fv antibody fragment with 99m Tc.
abstract: From genetic material of hybridoma cells, we have generated a recombinant single-chain antibody fragment (scFv antibody) specific to carcinoembryonic antigen (CEA), which can substitute an intact murine monoclonal immunoglobulin G1 (IgG1) antibody, also developed by our group, and used in clinical practice for many years. In this paper, we examine a novel one-step method for direct 99mTc labelling of a recombinant anti-CEA scFv fragment through a C-terminal peptide tag containing a six-histidine sequence. This C-terminal peptide tag does not affect antigen binding, and was employed as a strategy for the one-step method of direct 99mTc labelling of a recombinant antibody fragment, based on the criteria of Zamora and Rhodes (Zamora PO, Rhodes BA. Imidazoles as well as thiolates in proteins bind technetium-99m. Bioconj Chem 1992; 3: 493-498). This is a novel technique for the rapid labelling of molecules, suitable for in vivo trials. The method yields >95% labelling efficiency without major effects on biological or in vitro stability.
authors.affiliation: Department of Nuclear Medicine, National Institute of Oncology and Radiobiology, 29 y E, Vedado, La Habana 10400, Cuba. imagamma@infomed.sld.cu
authors.forename: G J
authors.initials: GJ
authors.lastname: Pimentel
authors.forename: J E
authors.initials: JE
authors.lastname: Vázquez
authors.forename: W
authors.initials: W
authors.lastname: Quesada
authors.forename: Y
authors.initials: Y
authors.lastname: Felipe
authors.forename: C
authors.initials: C
authors.lastname: Carderón
authors.forename: F M
authors.initials: FM
authors.lastname: Freyre
authors.forename: J P
authors.initials: JP
authors.lastname: Oliva
authors.forename: J V
authors.initials: JV
authors.lastname: Gavilondo
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D002272:Carcinoembryonic Antigen / Q000276:immunology; D002850:Chromatography, Gel; D002855:Chromatography, Thin Layer; D003545:Cysteine; D006639:Histidine / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D007135:Immunoglobulin Variable Region / Q000737:chemistry*; D007553:Isotope Labeling; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D010446:Peptide Fragments / Q000737:chemistry* / Q000493:pharmacokinetics; D011786:Quality Control; D019275:Radiopharmaceuticals / Q000737:chemistry* / Q000493:pharmacokinetics; D011994:Recombinant Proteins; D013667:Technetium / Q000737:chemistry* / Q000493:pharmacokinetics; D014018:Tissue Distribution
chemical_list: D000911:Antibodies, Monoclonal; D002272:Carcinoembryonic Antigen; D007135:Immunoglobulin Variable Region; D010446:Peptide Fragments; D019275:Radiopharmaceuticals; D011994:Recombinant Proteins; D006639:Histidine; D013667:Technetium; D003545:Cysteine