Abstract The brain-derived neurotrophic factor had nutrition, repair and protection functions to neurons of central nervous system, but its utilization was restricted by the blood-brain barrier. This paper used the single-chain antibody (ox26-scFv) to transferrin receptor(TfR) as vector to transport BDNF. The ox26-scFv gene and BDNF gene were amplified by PCR from plasmid PUC19/ ox26-scFv and plasmid PUC19/BDNF, inserted into the prokaryotic expression vector pTIG-Trx which carried a thioredoxin (Trx) gene and a C-terminal His.tag separately, constructed a pTIG-Trx/scFv-BDNF recombinant plasmid. The ScFv-BDNF fusion proteins were expressed at 20℃, after 0.02mM IPTG induction in the strain E.coli BL21(DE3). The soluble ScFv proteins in cytoplasm suspension were purified by immobilized metal chelation affinity chromatography(Ni-NTA), a single band with molecular weight 41 kD appeared on SDS-PAGE gel. Immunocytochemistry staining showed that ScFv-BDNF fusion proteins could recognize and bind to transferrin receptors on the surfaces of rat GH3 cells, and the fusion proteins could promote growth of the chick embryo dorsal root ganglion (DRG), which indicated that the fusion proteins not only could combine with transferrin receptors specially but also had biological activity of BDNF. These results would lay groundwork to transport BDNF across BBB as a CNS therapeutics.
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