Expression of platelet collagen receptor-glycoprotein VI fragment in E. coli and its biological activities / 中国实验血液学杂志

This study was aimed to further investigate the function of platelet collagen receptor-glycoprotein VI and to screen its specific inhibitor. The extracellular domain of platelet glycoprotein VI (GPVI) in E. coli was expressed by recombinant technology, the extracellular domain cDNA of GPVI was amplified from pBluescript KS(-)-GPVI plasmid by PCR. Proved by sequencing, the expression vector pET-20b(+)-GPVI was constructed, which was then transformed into E. coli (BL21(DE3)pLysS) and induced by IPTG. The recombinant GPVI was purified on Ni-NTA resin column and renatured in PBS containing GSH and GSSG. The anti-penta His McAb and anti-GPVI polyclonal antibody were used to identify the recombinant GPVI in Western blotting. Collagen binding test was conducted to investigate the biological activity of recombinant GPVI. The results showed that the recombinant GPVI was expressed in E. coli and successfully purified, which was confirmed to be similar to the native GPVI in Western blotting. The recombinant GPVI can bind the type I collagen in dose-dependent manner. In conclusion, the recombinant GPVI can be achieved in E. coli and restore its native characteristics after renaturation.

Expression of von willebrand factor-A3 domain in E coli and its biological function / 中国实验血液学杂志

The interaction among collagen, von Willebrand factor (vWF) and glycoprotein Ib axis is the first step in hemostasis and thrombosis, especially under high shear condition. To develop a new remedy of anti-thrombosis, mRNA from endothelial cells was extracted, and reverse transcription PCR was adopted to amplify DNA of interest. After sequencing, recombinant expression vector was constructed. The amplified DNA fragment of vWF domain A3 was inserted into expression vector with 6 x his taq, pET20b(+), the recombinant was transformed into E coli (strain DE3) and induced by IPTG. Recombinant vWF-A3 was designated as a recombinant fragment comprising residues 918 - 1114 of mature vWF subunit. It was purified through Ni-NTA resin column and refolded in Tris buffer containing GSH and GSSG. The results showed that rvWF-A3 was expressed successfully in E coli (strain DE3), accounting for 46% of total bacterial protein with its purity of over 95%. It was identified that rvWF-A3 is capable to bind collagen and inhibit the wild vWF binding to collagen by competition. It is concluded that rvWF-A3 fragment might be an effective antithrombotic agent for preventing arterial thrombosis.

Molecular cloning of human vWF/A1 gene and its expression / 中国实验血液学杂志

To study the mechanism of thrombogenesis and search new anti-thrombotic agent, the cDNA for human vWF A1 domain was high-level expressed in E. coli and recombinant protein of vWF A1 with biologic activity was obtained. The gene encoding A1 domain was amplified by PCR from plasmid containing full length cDNA of human vWF. After confirming by DNA sequencing analysis, the recombinant expression plasmid pQE31-vWF/A1 was constructed and introduced into E. coli M15 strain, then induced by IPTG; the expressed protein was purified with Ni-NTA agarose, identified by Western blotting. The results showed that the 854 bp DNA fragment was obtained by PCR from the plasmid containing full length cDNA for human vWF and its sequence was identical to the published sequence. High level expression of A1 protein was yielded after 5 hour-induction, which amounted to 30% of total bacteria protein in inclusion body. Western blot demonstrated it possessed good antigenicity and high specificity. It is concluded that cDNA for vWF/A1 had been cloned successfully, high level expression of A1 protein was achieved in E. oli. This study will provide a basis for the further clinical and basic research on the role of vWF in thrombosis and hemostasis.