Abstract
Angiotensinogen, a plasma serpin, functions as a donor of the decapeptide angiotensin I, which is cleaved from the N-terminus by renin. To assess the contribution of the serpin framework to peptide cleavage we produced a chimaeric molecule of alpha1-antitrypsin carrying the angiotensinogen N-terminus and determined the kinetic parameters for angiotensin I release. The Km for plasma angiotensinogen was 18-fold lower than for the chimaeric protein while the catalytic efficiency was four-fold higher. We also show that Cys-18 participates in a disulphide bond and propose that constraints on the N-terminus profoundly affect the interaction with renin.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Angiotensinogen / chemistry
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Angiotensinogen / metabolism*
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Catalysis
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Cloning, Molecular
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Cysteine
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Disulfides
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Escherichia coli
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Humans
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Kinetics
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Models, Molecular
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Molecular Sequence Data
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Mutagenesis, Insertional
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Ovalbumin / chemistry
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Protein Conformation*
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Protein Structure, Secondary
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Recombinant Fusion Proteins / chemistry
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Recombinant Fusion Proteins / metabolism
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Recombinant Proteins / metabolism
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Renin / metabolism*
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Sequence Alignment
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Sequence Homology, Amino Acid
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alpha 1-Antitrypsin / chemistry
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alpha 1-Antitrypsin / metabolism
Substances
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Disulfides
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Recombinant Fusion Proteins
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Recombinant Proteins
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alpha 1-Antitrypsin
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Angiotensinogen
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Ovalbumin
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Renin
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Cysteine