MW: 6984,50 Da. Lepirudin is a recombinant hirudin[1] derived from yeast cells. It is almost identical to hirudin extracted from Hirudo medicinalis. It differs by the substitution of leucine for isoleucine at the N-terminal end of the molecule and the absence of a sulfate group on the tyrosine at position 63 This protein is from E. coli.