Promucetin, a new C-type lectin-like protein modulates coagulation by activating platelets via GPIb.

Background: Snake venom C-type lectin-like proteins (also known as snaclecs) have anticoagulation and procoagulation effects by targeting platelet or coagulation factor IX/X, suggesting their potential as candidates for new anticoagulant drugs. Therefore, this study aims to evaluate the antiplatelet and antithrombotic effects of a new snaclec from Protobothrops mucrosquamatus venom and its potential as an anticoagulant candidate.

Methods: Promucetin was purified through sequential column chromatography, and its molecular mass was determined by SDS-PAGE. The α- and β-chains of promucetin were identified using liquid chromatography-mass spectrometry (LC-MS). In vitro analyses of platelet aggregation were performed using turbidimetric methods, thromboelastography, and coagulation activity assays. For in vivo experiments, promucetin was administered to rats at varying concentrations, and platelet changes were monitored. The antithrombotic effects of promucetin were assessed using a FeCl₃-induced rat thrombosis model.

Results: Promucetin existed as two multimers with molecular weights of 140.1 kDa and 91.9 kDa under non-reducing conditions. Sequence analysis revealed that its α-chain and β-chain shared 71% and 34% homology, respectively, with TMVA from the same snake venom. In vitro platelet aggregation assays indicated that promucetin activated platelets via glycoprotein Ib. Thromboelastography showed that promucetin inhibited both coagulation factor activity and platelet function, resulting in an anticoagulant effect. Specifically, thrombin time was prolonged, while activated partial thromboplastin time and prothrombin time remained unchanged. In vivo, promucetin administration led to a dose-dependent decrease in platelet count. At doses of 25 and 50 μg/kg, promucetin significantly inhibited thrombosis, with inhibition rates of 40.9% and 74.4%, respectively. For comparison, lysine acetylsalicylate produced an inhibition rate of 36.7%.

Conclusion: Promucetin exhibits significant ability to modulate coagulation function and effectively inhibit thrombosis by activating platelet via GPIb and reducing platelet count, which helps us understand its biological function in snake bites, it exhibits the potential to be a candidate for anticoagulant therapy.