Abstract: Objective  To clone and express Plasmodium falciparum erythrocyte membrane protein 1 DBLα （PfEMP1-DBLα） and three fragments genes, and screen the strongest affinity sequence with the red blood cell surface receptors?鄄heparin or heparin sulfate in the structure of PfEMP1-DBLα.  Methods  The sequence of PfEMP1-DBLα1245 was optimized according to the characteristics of E. coli codon, synthesized, and divided into three fragments （DBLαA, DBLαB, and DBLαC） by PCR. Full-length gene and three gene fragments were subcloned into PGEX-4T-1 vector, and transformed into E. coli BL21 and then induced with IPTG for expression. The recombinant protein was purified from bacterial lysates using gluthathione-Sepharose 4B. Heparin affinity test and glycosaminoglycan (GAG) inhibition test were used to analyze the affinity between recombinant protein and heparin.  Results  Four recombinant proteins（DBLα1245, DBLαA, DBLαB, and DBLαC） were expressed as solubility and the relative molecular weight （Mr 73 600, Mr 41 600, Mr 42 500, and Mr 41 500） were conformed to the prediction size. Heparin affinity test and GAG inhibition test showed that the four recombinant proteins were binded to the heparin-Sepharose, but not for the GST control. DBLαC (Q285-Y415) had the strongest affinity to heparin.  Conclusion  The strongest affinity sequence with heparin or heparin sulfate in the structure of PfEMP1?鄄DBLα is Q285-Y415, which plays a role in binding of Plasmodium falciparum infected red blood cells to the peripheral red blood cells.

Key words: Plasmodium falciparum, Membrane protein, Heparin