Abstract: The expression of recombinant soluble FGF-21 protein was achieved through transferring another plasmid pTf16 which expressed molecular chaperone Tig. On the other hand, the yield of FGF-21 was greatly improved with the method of lactose auto-induction. The result showed that the soluble TrxA-FGF-21 fusion protein reached 92.4% by molecular chaperone co-expression. With lactose auto-induction, the expression quantity of fusion protein was 17.4% of the total proteins, and the 〖WTBX〗OD600 〖WTBZ〗 was 12.4; thus relative yield was 5.5 times higher than IPTG induction. The biological activities of recombinant FGF-21 were studied 〖WTBX〗in vivo〖WTBZ〗 in healthy C57BL/6 mice. It showed that recombinant FGF-21 can lower blood glucose obviously in mice (〖WTBX〗P〖WTBZ〗 <0.05 or 〖WTBX〗P 〖WTBZ〗<0.01). The recombinant FGF-21 treatment also led to a significant decrease in concentration of triglyceride in C57BL/6 mice (〖WTBX〗P〖WTBZ〗 <0.01).

Key words: fibroblast growth factor 21, molecular chaperone, lactose auto-induction