Coagulation factor X polypeptides with modified activation properties
The present invention relates to modified cDNA sequences coding for factor X polypeptides, in particular human factor X and its derivatives which can bypass the need for either factor VIIIa/factor IXa or factor VIIa/tissue factor for activation. The invention relates further to recombinant expression vectors containing such modified cDNA sequences, host cells transformed with such recombinant expression vectors, recombinant polypeptides and derivatives which do have biological activities of the unmodified wild type protein but having altered activation properties, and processes for the manufacture of such recombinant proteins and their derivatives. The invention also covers a transfer vector for use in human gene therapy, which comprises such modified DNA sequences.
1. A biologically active factor X variant, comprising a full-length factor X polypeptide sequence with a modified factor X activation peptide, wherein the modified activation peptide has a formula of —R 1 —P—R 2 —wherein P is a polypeptide sequence cleavable by a serine protease, R 1 is a chemical bond or one or more amino acids, and R 2 is a chemical bond or one or more amino acids, wherein the modified activation peptide of —R 1 —P—R 2 —consists of a polypeptide sequence having a total length of 3-9 amino acids and the P is not present within an activation peptide of a wild type factor X (amino acid positions Ser183 through Arg234 of SEQ ID NO:2) and replaces the activation peptide of the wild type Factor X, wherein cleavage at the P by the serine protease activates the factor X variant, wherein the serine protease is factor IIa, factor IXa, factor Xa, factor XIa, factor XIIa, activated protein C, elastase, or kallikrein, and is not furin4 and wherein the factor X variant has factor X coagulant activity.
2. The factor X variant according to claim 1 , wherein the factor X variant has an enhanced haemostatic bypassing activity compared to that of a factor X variant wherein —R 1 —P—R 2 —consists of the amino acid sequence of SEQ ID NO:3.
3. The factor X variant according to claim 1 , wherein the factor X variant has an enhanced haemostatic bypassing activity compared to that of a factor X variant wherein —R 1 —P—R 2 —consists of the amino acid sequence Glu226-Gln227-Ser228-Phe229-Asn230-Asp231-Phe232-Thr233-Arg234 (SEQ ID NO:10).
4. A pharmaceutical composition comprising the factor X variant according to claim 1 and a pharmaceutically acceptable carrier or excipient.