Cloning and Expression of Annexin V cDNA in E.coli

The cDNA encoding the mature annexin V was isolated by using RT-PCR method from total RNAs of fresh human placenta. The result of sequencing indicated that the sequence of isolated annexin V cDNA was the same as the reported nucleotide sequence of annexin V. The annexin V cDNA was cloned into expression plasmid pET24a(+) under T7 promoter and then transformed into E.coli BL21(DE3). SDS-PAGE analysis revealed that the human annexin V was highly expressed and accumulated up to 38% of total bacterial proteins in soluble form after the induction by 1 mmol/L IPTG. The purified human annexin V can significantly prolong activated partial thromboplastin time (APTT).