Biological Activity of Brain-derived Neurotrophic Factor with Mismatched Disulfide Linkages Produced by Escherichia coli

E. coli cells harboring an expression plasmid with a brain-derived neurotrophic factor (BDNF) gene obtained from rat BDNF cDNA were sonicated and centrifuged to obtain a precipitate containing BDNF. Ten different proteins of BDNF were purified from the precipitate and the three disulfide linkages of six proteins were identified. Those disulfide structures were different from that of authentic BDNF and the biological activities of BDNF with mismatched disulfide linkages (EC50 of 2 to 15ng/ml) were much lower than that of authentic BDNF (EC50 of 30pg/ml). The BDNF with mismatched disulfide linkages inhibited the biological activity of authentic BDNF.