Hemextin A (monomer): exhibits mild anticoagulant activity. It specifically inhibits the activation of FX (F10) by the TF-FVIIa complex (extrinsic tenase complex (ETC)) by non-competitively inhibiting the enzymatic activity of FVIIa. Hemextin AB complex: specifically inhibits the activation of FX (F10) by the TF-FVIIa complex (extrinsic tenase complex (ETC)) (IC(50)= 100 nM, Ki=25 nM) by non-competitively inhibiting the enzymatic activity of FVIIa. Heterotetramer composed of two A and two B chains; non-covalently linked. Does not exists as a complex in the crude venom. Expressed by the venom gland. May contain several disulfide bonds. Belongs to the snake three-finger toxin family. Short-chain subfamily. Type IB cytotoxin sub-subfamily.