Research

Heme/Thrombosis Research

Heme (iron(II/III)-protoporphyrin IX) is primarily known for its role as an oxygen-binding, prosthetic group of hemoglobin and circulates as such in amounts of ~25 trillion molecules in the erythrocytes in blood of a human body. In the course of intravascular hemolysis, which can occur in diseases such as sickle cell anemia or as a result of transfusions, the erythrocytes are destroyed prematurely, leading to a massive release of hemoglobin and consequently to an accumulation of labile heme in the intravascular compartment. In this form, heme can transiently bind to proteins and affect their stability and/or function [1-3].
One of the main complications of hemolytic events are venous prothrombotic coagulation disorders, such as deep vein thrombosis or pulmonary embolism. Their molecular basis has not yet been fully elucidated, but there are indications that labile heme and its interaction with plasma proteins involved in these processes also play a role [4,5]. These heme-protein interactions are largely unexplored both at the molecular level and in the context of their (patho-)physiological relevance. As previously shown with the endogenous coagulation inhibitor APC [6], our DFG- and GTH-funded projects (see projects below) now aim to investigate and characterize the coagulation system as a heme-regulated system at the level of potential heme-protein interactions using protein-derived peptides.

[1] Soares, M. P., Bozza, M. T. (2016) Red alert: Heme is an alarmin. Curr. Opin. Immunol. 38, 94-100.
[2] Roumenina, L. T., Rayes, J., Lacroix-Desmazes, S., Dimitrov, J. D. (2016) Heme: Modulator of plasma systems in hemolytic diseases. Trends Mol. Med. 22(3), 200-213.
[3] Kühl, T., Imhof, D. (2013) Regulatory FeII/III heme: The reconstruction of a molecule's biography. ChemBioChem 15(14), 2024-2035.
[4] Hopp, M.-T., Imhof, D. (2021) Linking labile heme with thrombosis. J. Clin. Med. 10(3), 427.
[5] Mubeen, S., Domingo-Fernandez, D., Díaz del Ser, S., Solanki, D., Kodamullil, A. T., Hofmann-Apitius, M., Hopp, M.-T., Imhof, D. (2022) Exploring the complex network of heme-triggered effects on the blood coagulation system. J. Clin. Med. 11(19), 5975.
[6] Hopp, M.-T., Alhanafi, N., Paul George, A. A., Hamedani, N. S., Biswas, A., Oldenburg, J., Pötzsch, B., Imhof, D. (2021) Molecular insights and functional consequences of the interaction of heme with activated protein C. Antioxid. Redox Signal. 34(1), 32-48.

Methods

> Solid-phase peptide synthesis (SPPS)

> Peptide and protein purification (HPLC, SEC)

> Peptide and protein analytics (e.g., HPLC, FPLC, LC-ESI-MS, MALDI-TOF-MS, sequencing by MS/MS, amino acid analysis, SDS-PAGE, UV/Vis spectroscopy)

> Binding studies for the characterization of protein-ligand interactions (e.g., UV/Vis spectroscopy, SPR spectroscopy in silico studies)

> Functional assays (e.g., chromogenic assays for enzymatic activity testing, clinical diagnostic assays, and physiologically relevant assay systems)

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