An isolated polypeptide comprising (A) (i) the amino acid sequence of SEQ ID NO. 12 or 13 further comprising a modification in the autolysis loop of the heavy chain of SEQ ID NO. 12 or 13 or (ii) an amino acid sequence that has at least 95% sequence identity with SEQ ID NO. 12 or 13, and further comprising one or more mutations selected from the group consisting of Arg366Q / A, Lys370Q / A, Arg372Q / A, Arg376Q / A, and combinations thereof； wherein the autolysis loop corresponds to amino acid residues 366-376 of SEQ ID NO. one； (B) the amino acid sequence of SEQ ID NO. 20 or an amino acid sequence that has at least 95% sequence identity with SEQ ID NO. 20, in which the polypeptide does not contain the C-terminal end of wild-type factor Xa after the remaining amino acid corresponding to Arg429 of SEQ ID NO. 3； (C) the amino acid sequence of SEQ ID NO. 21 or an amino acid sequence that has at least 95% sequence identity with SEQ ID NO. 21, in which the polypeptide has Gln in the amino acid residue corresponding to Arg429 of SEQ ID NO. 3； or (D) the amino acid sequence of SEQ ID NO. 22 or an amino acid sequence that has at least 95% sequence identity with SEQ ID NO. 22, in which the polypeptide has Gln in the amino acid residue corresponding to Arg429 of SEQ ID NO. 3, and has Ala in the amino acid residue corresponding to Thr443 of SEQ ID NO. 3, in which the polypeptide (a) has a reduced procoagulant activity compared to wild-type factor Xa, (b) is capable of binding to a factor Xa inhibitor, and (c) is not assembled into a complex of prothrombinaseUn polipéptido aislado que comprende (A) (i) la secuencia de aminoácidos de SEQ ID NO. 12 o 13 que comprende adicionalmente una modificación en el bucle de autolisis de la cadena pesada de la SEQ ID NO. 12 o 13 o (ii) una secuencia de aminoácidos que tiene al menos el 95 % de identidad de secuencia con la SEQ ID NO. 12 o 13, y que comprende adicionalmente una o más mutaciones seleccionadas entre el grupo que consiste en Arg
