Isolation and characterisation of an anticoagulant oligopeptide from blue mussel, Mytilus edulis

A potent anticoagulant oligopeptide was isolated from the edible parts of blue mussel (Mytilus edulis). M. edulis anticoagulant peptide (MEAP) with an approximately 2.5 kDa molecular mass was similar to the amino acid sequence of the EF-hand domain of calmodulin from scallop adductor muscle. MEAP could potently prolong both the thrombin time and the activated partial thromboplastin time, and specifically interact with blood coagulation factors: FIX, FX, and FII. MEAP could inhibit proteolytic activation of FX by the intrinsic FXase and formation of FIIa by a prothrombinase complex in dose-dependant reactions. This study elucidated that MEAP prolonged blood clotting by inhibiting activation of FX in the intrinsic tenase complex (FIXa/VIIIa/PLs) and conversion of FII to FIIa in the prothrombinase complex (FXa/FVa/PLs).