Fritz Markwardt

Importance to Hirudotherapy

Fritz Markwardt is the most important figure in 20th-century hirudotherapy science. His 1957 Naturwissenschaften paper, written under difficult East German laboratory conditions with limited Western reagents, achieved what Haycraft and Jacoby could only approximate: crystalline-grade hirudin. Using ion-exchange chromatography on cellulose phosphate columns — equipment Markwardt's team had to fabricate in-house — he separated hirudin from the dozens of contaminating leech proteins, then characterized its primary structure with techniques borrowed from insulin chemistry pioneered at Cambridge. Markwardt's mechanistic studies between 1958 and 1985 essentially defined the field of direct thrombin inhibition. He showed that hirudin binds thrombin with a dissociation constant of ~0.5 pM — the tightest non-covalent protein-protein interaction then known in biochemistry. He demonstrated that this binding was stoichiometric (1:1) and reversible, distinguishing hirudin from heparin's catalytic mechanism. He correctly predicted that synthetic peptide fragments of hirudin (later realized as bivalirudin) could replicate the parent molecule's pharmacology with shorter half-life and better dose-control. Every modern direct oral anticoagulant — dabigatran, argatroban, lepirudin, desirudin, bivalirudin — traces a direct intellectual lineage to Markwardt's bench. When the Berlin Wall fell in 1989, Markwardt was suddenly able to collaborate openly with Western pharma. Hoechst, Bayer, and Boehringer Mannheim all sent senior scientists to Greifswald in the early 1990s. The result was the world's first recombinant hirudin (lepirudin / Refludan) approved by FDA in 1998 for heparin-induced thrombocytopenia. Markwardt lived to see his 1957 purification become the basis of a billion-dollar drug class — and at his death in 2011, the German Pharmacological Society renamed its annual anticoagulation prize the 'Fritz-Markwardt-Preis' in his honor.