title: Enhanced fluorescence resonance energy transfer immunoassay with improved sensitivity based on the Fab'-based immunoconjugates.
abstract: Fluorescence resonance energy transfer (FRET) is a powerful technique to monitor protein-protein interaction. Recently, we developed homogeneous and noncompetitive immunoassay based on the enhanced FRET by leucine zipper interaction. Here we improved the assay by establishing a general method for preparation of the Fab'-based immunoconjugate. Anti-human serum albumin Fab' numbers 11 and 13 were chemically conjugated with recombinant proteins consisting of thioredoxin, flexible linker, and green fluorescent protein color variant tethered with a leucine zipper motif. Compared with single chain antibody variable region-based fusion proteins prepared by the gene fusion method in our previous study, the resultant Fab'-based immunoconjugates accomplished an assay with nearly 10 times greater sensitivity. Furthermore, the conjugation method enabled us to apply the assay generally to measurement of another high-molecular weight antigen for which antibodies prepared for sandwich immunoassay are commercially available. Because of the facility and generality of the preparation method for the immunoconjugate, the assay is expected to be applied to many antigens that require rapid diagnosis and moderate measurement range.
authors.affiliation: Biochemical Research Laboratory, Eiken Chemical Co., LTD., 143 Nogi, Nogi-machi, Shimotsuga-gun, Tochigi 329-0114, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ohiro
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ueda
authors.forename: Norio
authors.initials: N
authors.lastname: Shibata
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Nagamune
mesh_terms: D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007118:Immunoassay / Q000379:methods; D018796:Immunoconjugates / Q000032:analysis* / Q000737:chemistry; D007140:Immunoglobulin Fab Fragments / Q000032:analysis* / Q000737:chemistry; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence
chemical_list: D018796:Immunoconjugates; D007140:Immunoglobulin Fab Fragments; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins