Refine
Has Fulltext
- no (7)
Document Type
- Article (7)
Language
- English (7)
Is part of the Bibliography
- yes (7)
Keywords
- Cell-free (1)
- In vitro translation (1)
- Insect lysate (1)
- Single chain antibody (scFv) (1)
- Surface plasmon resonance (1)
Institute
Characterization of a monoclonal antibody and its Fab fragment against diphenylurea hapten with BIA
(1998)
A recombinant single chain antibody fragment (designated scDE1) of the murine monoclonal anti-fluorescein antibody B13-DE1 was generated using the original hybridoma cells as source for the variable antibody heavy and light chain (VH and VL) genes. After cloning the variable genes into a phage vector a functional antibody fragment was selected by phage display panning. Recombinant antibody could be expressed as phage antibody and as soluble single chain antibody in Escherichia coli. High yield of scDE1 could also be detected in bacterial culture supernatant. The scDE1 showed the same binding specificity as the parental monoclonal antibody, i.e. it bound fluorescein, fluorescein derivatives and a fluorescein peptide mimotope. Surface plasmon resonance revealed a K(D) of 19 nM for the scDE1 compared to 0.7 nM for the monoclonal antibody. The isolated soluble scDE1 could easily be conjugated to horseradish peroxidase which allowed the use of the conjugate as universal indicator for the detection of fluorescein-labelled proteins in different immunoassays. Detection of hCG in urine was performed as a model system using scDE1. In addition to E. coli the scFv genes could also be transferred and expressed in eukaryotic cells. Finally, we generated HEK293 cells expressing the scDE1 at the cell surface.
Cell-free protein synthesis is of increasing interest for the rapid and high-throughput synthesis of many proteins, in particular also antibody fragments. In this study, we present a novel strategy for the production of single chain antibody fragments (scFv) in a eukaryotic in vitro translation system. This strategy comprises the cell-free expression, isolation and label-free interaction analysis of a model antibody fragment synthesized in two differently prepared insect cell lysates. These lysates contain translocationally active microsomal structures derived from the endoplasmic reticulum (ER), allowing for posttranslational modifications of cell-free synthesized proteins. Both types of these insect cell lysates enable the synthesis and translocation of scFv into ER-derived vesicles. However, only the one that has a specifically adapted redox potential yields functional active antibody fragments. We have developed a new methodology for the isolation of functional target proteins based on the translocation of cell-free produced scFv into microsomal structures and subsequent collection of protein-enriched vesicles. Antibody fragments that have been released from these vesicles are shown to be well suited for label-free binding studies. Altogether, these results show the potential of insect cell lysates for the production, purification and selection of antibody fragments in an easy-to-handle and time-saving manner.