Factor IX: Difference between revisions

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The serine protease domain of FIX is required for blood coagulation. FIX circulates in plasma as a single-chain zymogen at a concentration of 2.5-5 mg/ml and a half life is approximately 24 hours. The zymogen is activated by either FVII–tissue-factor complex or Factor XIa (FXIa). During activation the peptide bonds betweennArg145–Ala146 and Arg180–Val181 are cleaved releasing an 11 kDa activation peptide from the Factor IX. This cleavage allows the exposure of the serine protease site on the heavy chain which can then activate Factor X in the presence of Factor VIII, Ca and phospholipid surface. This enzyme belongs to the family of trypsin-like serine proteases.The mechanism of these serine proteases involves the catalytic triad, which is found in the enzymes active site and is composed of three amino acids. The serine protease domain of FIX accounts for half of its mass and contains a conserved catalytic triad made of Asp, His, and Ser. The binding pockets of these vitamin-K depended proteases recognize a small number of amino acids sequences allowing them to cleave at arginyl residues with high substrate specificity. Serine’s hydroxyl group carries out the nucleophillic attack. While the imidazol ring of hisidine takes up the liberated proton and the carboxylate ion of Asp stabilizes the developing charge. Unlike other serine protease family members these vitamin K dependent proteases have an extended specificity pocket which allows a small number of amino acids to be recognized.

The serine protease domain of FIX is required for blood coagulation. FIX circulates in plasma as a single-chain zymogen at a concentration of 2.5-5 mg/ml and a half life is approximately 24 hours. The zymogen is activated by either FVII–tissue-factor complex or Factor XIa (FXIa). During activation the peptide bonds betweennArg145–Ala146 and Arg180–Val181 are cleaved releasing an 11 kDa activation peptide from the Factor IX. This cleavage allows the exposure of the serine protease site on the heavy chain which can then activate Factor X in the presence of Factor VIII, Ca and phospholipid surface. This enzyme belongs to the family of trypsin-like serine proteases.The mechanism of these serine proteases involves the catalytic triad, which is found in the enzymes active site and is composed of three amino acids.

The serine protease domain of FIX accounts for half of its mass and contains a conserved catalytic triad made of Asp, His, and Ser. The binding pockets of these vitamin-K depended proteases recognize a small number of amino acids sequences allowing them to cleave at arginyl residues with high substrate specificity. Serine’s hydroxyl group carries out the nucleophillic attack. While the imidazol ring of hisidine takes up the liberated proton and the carboxylate ion of Asp stabilizes the developing charge. Unlike other serine protease family members these vitamin K dependent proteases have an extended specificity pocket which allows a small number of amino acids to be recognized.

Factor IX: Difference between revisions

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-The serine protease domain of FIX is required for blood coagulation. FIX circulates in plasma as a single-chain zymogen at a concentration of 2.5-5 mg/ml and a half life is approximately 24 hours. The zymogen is activated by either FVII–tissue-factor complex or Factor XIa (FXIa). During activation the peptide bonds betweennArg145–Ala146 and Arg180–Val181 are cleaved releasing an 11 kDa activation peptide from the Factor IX. This cleavage allows the exposure of the serine protease site on the heavy chain which can then activate Factor X in the presence of Factor VIII, Ca and phospholipid surface. This enzyme belongs to the family of trypsin-like serine proteases.The mechanism of these serine proteases involves the catalytic triad, which is found in the enzymes active site and is composed of three amino acids. The serine protease domain of FIX accounts for half of its mass and contains a conserved catalytic triad made of Asp, His, and Ser. The binding pockets of these vitamin-K depended proteases recognize a small number of amino acids sequences allowing them to cleave at arginyl residues with high substrate specificity. Serine’s hydroxyl group carries out the nucleophillic attack. While the imidazol ring of hisidine takes up the liberated proton and the carboxylate ion of Asp stabilizes the developing charge. Unlike other serine protease family members these vitamin K dependent proteases have an extended specificity pocket which allows a small number of amino acids to be recognized.
+The serine protease domain of FIX is required for blood coagulation. FIX circulates in plasma as a single-chain zymogen at a concentration of 2.5-5 mg/ml and a half life is approximately 24 hours. The zymogen is activated by either FVII–tissue-factor complex or Factor XIa (FXIa). During activation the peptide bonds betweennArg145–Ala146 and Arg180–Val181 are cleaved releasing an 11 kDa activation peptide from the Factor IX. This cleavage allows the exposure of the serine protease site on the heavy chain which can then activate Factor X in the presence of Factor VIII, Ca and phospholipid surface. This enzyme belongs to the family of trypsin-like serine proteases.The mechanism of these serine proteases involves the catalytic triad, which is found in the enzymes active site and is composed of three amino acids.
+The serine protease domain of FIX accounts for half of its mass and contains a conserved catalytic triad made of Asp, His, and Ser. The binding pockets of these vitamin-K depended proteases recognize a small number of amino acids sequences allowing them to cleave at arginyl residues with high substrate specificity. Serine’s hydroxyl group carries out the nucleophillic attack. While the imidazol ring of hisidine takes up the liberated proton and the carboxylate ion of Asp stabilizes the developing charge. Unlike other serine protease family members these vitamin K dependent proteases have an extended specificity pocket which allows a small number of amino acids to be recognized.