Leeches (Hirudo medicinalis) have been used medicinallyfor centuries to treat injuries in which blood engorges thetissues. The logic behind this is solid: leeches produce anagent known as hirudin that is a potent, specific thrombininhibitor. Leeches have been used to prevent thrombosisin the microvasculature of reattached digits. Lepirudin(Refludan) is an rDNA-derived protein produced in yeast. Ithas a molecular mass of approximately 7,000 Da. Lepirudindiffers from the natural polypeptide, in that it has an Nterminalleucine instead of isoleucine and is missing a sulfatefunction at Tyr63.
