Abstract
Uncontrollable bleeding is still a worldwide killer. In this study, we aimed to investigate a novel approach to exhibit effective haemostatic properties, which could possibly save lives in various bleeding emergencies. According to the structure-based enzymatic design, we have engineered a novel single-chain hybrid enzyme complex (SCHEC), COX-1-10aa-TXAS. We linked the C-terminus of cyclooxygenase-1 (COX-1) to the N-terminus of the thromboxane A(2) (TXA(2) ) synthase (TXAS), through a 10-amino acid residue linker. This recombinant COX-1-10aa-TXAS can effectively pass COX-1-derived intermediate prostaglandin (PG) H(2) (PGH(2) ) to the active site of TXAS, resulting in an effective chain reaction property to produce the haemostatic prostanoid, TXA(2) , rapidly. Advantageously, COX-1-10aa-TXAS constrains the production of other pro-bleeding prostanoids, such as prostacyclin (PGI(2) ) and prostaglandin E(2) (PGE(2) ), through reducing the common substrate, PGH(2) being passed to synthases which produce aforementioned prostanoids. Therefore, based on these multiple properties, this novel COX-1-10aa-TXAS indicated a powerful anti-bleeding ability, which could be used to treat a variety of bleeding situations and could even be useful for bleeding prone situations, including nonsteroidal anti-inflammatory drugs (NSAIDs)-resulted TXA(2) -deficient and PGI(2) -mediated bleeding disorders. This novel SCHEC has a great potential to be developed into a biological haemostatic agent to treat severe haemorrhage emergencies, which will prevent the complications of blood loss and save lives.