Patent US 5,589,360

This invention particularly provides a novel polypeptide having high protease-inhibiting activity, preferably FXa-inhibiting activity, which comprises, an lease as a part of the polypeptide, an amino acid sequence resulting from substitution of an amino acid for at least one amino acid in the following amino acid sequence (1), wherein the amino acid substitution is at least one substitution selected from the following substitution means (i) to (iii). It also provides a process for the production of the polypeptide, a novel DNA fragment encoding the polypeptide and a drug composition containing the same. ______________________________________ Amino acid sequence (1) ______________________________________ Cys Asn Leu Pro Ile Val Arg Gly Pro Cys Arg Ala Phe Ile Gln Leu Trp Ala Phe Asp Ala Val Lys Gly Lys Cys Val Leu Phe Pro Tyr Gly Gly Cys Gln Gly Asn Gly Asn Lys Phe Tyr Ser Glu Lys Glu Cys Arg Glu Tyr Cys ______________________________________ PA1 (i) Substitution of 15 position Gln counting from the N-terminus by an amino acid other than Gln. PA1 (ii) Substitution of 42 position Tyr counting from the N-terminus by an amino acid other than Tyr. PA1 (iii) Substitution of 7 position Arg counting from the N-terminus by an amino acid other than Arg.