An isolated polypeptide that comprises (i) the amino acid sequence of SEQ ID NO. 12 or 13 which further comprises a modification at the autolysis loop of the heavy chain of SEQ ID NO. 12 or 13 or (ii) an amino acid sequence having at least 95% sequence identity to 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 to 376 of SEQ ID NO. 1; the amino acid sequence of SEQ ID NO. 20 or an amino acid sequence having at least 95% sequence identity to SEQ ID NO. 20, wherein the polypeptide does not contain the C-terminus of wild-type factor Xa after the amino acid residue corresponding to Arg429 of SEQ ID NO. 3; the amino acid sequence of SEQ ID NO. 21 or an amino acid sequence having at least 95% sequence identity to SEQ ID NO. 21, wherein the polypeptide has Gln at the amino acid residue corresponding to Arg 429 of SEQ ID NO. 3; or the amino acid sequence of SEQ ID NO. 22 or an amino acid sequence having at least 95% sequence identity to SEQ ID NO. 22, wherein the polypeptide has Gln at the amino acid residue corresponding to Arg429 of SEQ ID NO. 3, and has Ala at the amino acid residue corresponding to Thr443 of SEQ ID NO. 3, wherein the polypeptide (a) has reduced procoagulant activity compared to wild-type factor Xa, (b) is capable of binding to a factor Xa inhibitor, and (c) does not assemble into a prothrombinase complex. (i) the amino acid sequence of SEQ ID NO. 12 or 13 which further comprises a modification at the autolysis loop of the heavy chain of SEQ ID NO. 12 or 13 or (ii) an amino acid sequence having at least 95% sequence identity to 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 to 376 of SEQ ID NO. 1; (i) the amino acid sequence of SEQ ID NO. 12 or 13 which further comprises a modification at the autolysis loop of the heavy chain of SEQ ID NO. 12 or 13 or (ii) an amino acid sequence having at least 95% sequence identity to 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 to 376 of SEQ ID NO. 1; the amino acid sequence of SEQ ID NO. 20 or an amino acid sequence having at least 95% sequence identity to SEQ ID NO. 20, wherein the polypeptide does not contain the C-terminus of wild-type factor Xa after the amino acid residue corresponding to Arg429 of SEQ ID NO. 3; the amino acid sequence of SEQ ID NO. 21 or an amino acid sequence having at least 95% sequence identity to SEQ ID NO. 21, wherein the polypeptide has Gln at the amino acid residue corresponding to Arg 429 of SEQ ID NO. 3; or the amino acid sequence of SEQ ID NO. 22 or an amino acid sequence having at least 95% sequence identity to SEQ ID NO. 22, wherein the polypeptide has Gln at the amino acid residue corresponding to Arg429 of SEQ ID NO. 3, and has Ala at the amino acid residue corresponding to Thr443 of SEQ ID NO. 3,