Abstract: This invention refers to the process for obtaining the recombinant prothrombin activating protease (rLopap) in monomeric form, the recombinant prothrombin activating protease (rLopap), as well as its amino acid sequence. In addition to that, this invention also refers to the use of this protease for depleting the blood fibrinogen, and serve as diagnosis kit for dysprothrombinemias. This invention describes the obtainence in recombinant form and the characterization of a prothrombin activator protease of 21 kDa, named rLopap (Lonomia obliqua prothrombin activator protease), with serineproteases characteristics however it shows sequence of conserved amino acids as in a lipocalin family. The protein presents pro-coagulating activity, depleting blood fibrinogen and prolonging the coagulation time of human blood/plasma. The obtainence of rLopap in its recombinant form and showing adequate activity for allowing clinical Pharmacology essays is presented in this invention.