Novel antithrombotic antibody

A method for screening antithrombotic substance, comprising:

• (1) adding candidate substance to the system comprising FIXa and FVIIIa, wherein the FIXa and FVIIIa interact with each other:
• (2) detecting the interaction between FIXa and FVIIIa;
• if the candidate substance competes with FVIIIa to bind FIXa and reduces the formation of the FVIIIa-FIXa complex, it indicates that the candidate substance is a antithrombotic substance;
• wherein the binding sites of the candidate substance and the FIXa complex can be predicted by protein-docking method for measuring the binding of FIXa and FVIIIa protein, wherein functions of the candidate substance can be determined by observing the effect of the candidate substance in binding between FIXa and FVIIIa at the binding sites or adjacent sites of FIXa;
• wherein the binding sites or adjacent sites comprise:
• Asn93, Lys132, Arg165, Thr175;
• further comprises:
• Ala95, Lys98, Asp164, Lys173, Tyr177;
• further comprises:
• Lys126, Asn129, Asn178, Lys230, Arg233, Asn236;
• wherein the amino acid residues at the sites can form a cluster, occupying the common surface between c170-helix and c131-helix of the FIXa protein.