[Expression and identification of Bm-TFF2 in Pichia pastoris].

Bm-TFF2, an amphibian trefoil factor, which is isolated from skin secretions of frog Bombina maxima, has much stronger biological activities than human TFFs. In the present study, Bm-TFF2 gene was amplified by polymerase chain reaction (PCR) from its cDNA and cloned into Pichia pastoris expression vector pPIC9K containing AOX1 promoter and alpha -factor leader sequence. Multi-copies insertion transformants were screened on G418 plates. After the induction by 1% methanol for 72 hours, the expression of Bm-TFF2 came up to the best quantity which was about 50 mg in 1L medium, and 80% saturation ammonium sulfate was suitable to collect the Bm-TFF2 protein, as identified by SDS-PAGE and Western blotting assay. The results showed that the plasmid of Bm-TFF2-pPIC9K was constructed successfully and expressed abundantly in eukaryotic expression system, which lies basis for researching further the biological activities and the relationship of structure and functions of Bm-TFF2.