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PDBsum entry 4coq
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Enzyme class:
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E.C.4.2.1.1
- carbonic anhydrase.
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Reaction:
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hydrogencarbonate + H+ = CO2 + H2O
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hydrogencarbonate
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+
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H(+)
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=
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CO2
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+
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H2O
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Cofactor:
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Zn(2+)
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Molecule diagrams generated from .mol files obtained from the
KEGG ftp site
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DOI no:
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Acta Crystallogr D Biol Crystallogr
70:2607-2618
(2014)
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PubMed id:
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The structure of a tetrameric α-carbonic anhydrase from Thermovibrio ammonificans reveals a core formed around intermolecular disulfides that contribute to its thermostability.
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P.James,
M.N.Isupov,
C.Sayer,
V.Saneei,
S.Berg,
M.Lioliou,
H.K.Kotlar,
J.A.Littlechild.
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ABSTRACT
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Carbonic anhydrase enzymes catalyse the reversible hydration of carbon dioxide
to bicarbonate. A thermophilic Thermovibrio ammonificans α-carbonic anhydrase
(TaCA) has been expressed in Escherichia coli and structurally and biochemically
characterized. The crystal structure of TaCA has been determined in its native
form and in two complexes with bound inhibitors. The tetrameric enzyme is
stabilized by a unique core in the centre of the molecule formed by two
intersubunit disulfides and a single lysine residue from each monomer that is
involved in intersubunit ionic interactions. The structure of this core protects
the intersubunit disulfides from reduction, whereas the conserved intrasubunit
disulfides are not formed in the reducing environment of the E. coli host
cytosol. When oxidized to mimic the environment of the periplasmic space, TaCA
has increased thermostability, retaining 90% activity after incubation at 70°C
for 1 h, making it a good candidate for industrial carbon-dioxide capture. The
reduction of all TaCA cysteines resulted in dissociation of the tetrameric
molecule into monomers with lower activity and reduced thermostability. Unlike
other characterized α-carbonic anhydrases, TaCA does not display esterase
activity towards p-nitrophenyl acetate, which appears to result from the
increased rigidity of its protein scaffold.
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');
}
}
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