Anticoagulant activity of a natural protein purified from Hypomesus olidus

A novel anticoagulant protein (E-II-1) was separated and purified from Hypomesus olidus, a unique freshwater fish in northern China. E-II-1 had a molecular mass of approximately 40 kDa with no subunits. The high content of hydrophobic amino acids and negatively charged amino acids in E-II-1 demonstrated that the amino acid compositions might contribute to the anticoagulant activity. E-II-1 contained α-helices 16.75%, β-sheets 42.67%, β-turn 25.58% and random coil 15.00%. In vitro blood coagulation time assay, E-II-1 significantly prolonged the activated partial thrombin time in a dose-dependent manner. Results indicated that E-II-1 acted as anticoagulants through the endogenous pathway with an inhibition of FXa. The specific activity of E-II-1 was 103.50 U/mg at a concentration of 1.00 mg/mL. Therefore, E-II-1 might be one of the promising anticoagulants originated from natural food sources with more safety and less side effects.