Heme-Protein Interactions within the blood coagulation system: Implications for hemolysis-associated coagulation disorders

Introduction Intravascular hemolysis is associated with the release of heme into the circulation, a prooxidant molecule capable of disrupting endothelial function and immune responses. Increasing evidence suggests that labile heme also directly affects the coagulation system, contributing to thrombotic complications in hemolytic disorders such as sickle cell disease, paroxysmal nocturnal hemoglobinuria, and malaria. However, the molecular interactions between heme and the individual involved proteins remain poorly understood. This study thus sheds light on heme binding to select procoagulant and anticoagulant proteins, aiming to elucidate mechanisms by which hemolysis promotes coagulopathy. Method Heme binding to a panel of human blood coagulation proteins, including procoagulant factors and anticoagulant, was assessed using UV/Vis and SPR spectroscopy. To characterize respective heme-binding sites in these coagulation proteins, their amino acid sequences were screened for potential heme-binding motifs by using the webserver HeMoQuest. The heme-binding capacity of the predicted motifs was studied by protein-derived peptide as models. Structural consequences of heme binding were analyzed by molecular docking and molecular dynamics simulations. Functional impact of heme was investigated by chromogenic and clotting assays. Results Heme exhibited specific, concentration-dependent binding to several coagulation proteins with distinct heme-binding affinities. Structural analyses revealed that heme-induced conformational changes correlated with functional influences. Notably, the heme-induced effects appear paradoxical, as they promote both procoagulant and anticoagulant responses. Conclusion These results demonstrate that heme modulates the structure and function of coagulation proteins, contributing to coagulopathy observed in hemolytic conditions. Understanding these interactions offers novel insight into the pathophysiology of hemolysis-associated coagulation disorders and may guide the development of targeted therapeutic strategies to mitigate prothrombotic complications. Publication History Article published online: 17 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany