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PDBsum entry 1hcb
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Lyase(oxo-acid)
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PDB id
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1hcb
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References listed in PDB file
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Key reference
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Title
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Enzyme-Substrate interactions. Structure of human carbonic anhydrase i complexed with bicarbonate.
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Authors
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V.Kumar,
K.K.Kannan.
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Ref.
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J Mol Biol, 1994,
241,
226-232.
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PubMed id
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Note In the PDB file this reference is
annotated as "TO BE PUBLISHED".
The citation details given above were identified by an automated
search of PubMed on title and author
names, giving a
perfect match.
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Abstract
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The structure of HCAI-HCO3- complex has been refined with 10-1.6A X-ray
diffraction data to an R-value of 17.7%. The structure reveals monodentate
binding of the HCO3- anion at an apical tetrahedral position to the zinc ion.
The binding mode and interactions of HCO3- in HCAI differ from that in HCAII.
The activity linked H2O/OH- group in the free HCAI is replaced by the hydroxyl
group of the bicarbonate anion. This result rules out the rearrangement of the
bound HCO3- advocated earlier to explain the microscopic reversibility of the
catalysed reaction. From the geometry of the H-bonds between Glu106-Thr199 pair
and Glu117-His119 couple, the glutamic acids are expected to be ionized and
accept H-bonds from their partners. The product-inhibiton by HCO3- anion is
explained on the basis of proton localization on His119 in the Glu117-His119
couple. These results are consistent with the hypothesis that Glu117-His119
tunes the ionicity of the Zn2+ and the binding strength of HCO3- anion. A pi
hydrogen bond is observed between a water and phenyl ring of the Tyr114 residue.
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Secondary reference #1
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Title
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Structure of human carbonic anhydrase i complexed with gold cyanide inhibitor: inhibition mechanism
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Authors
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V.Kumar,
K.K.Kannan.
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Ref.
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acta crystallogr ,sect a, 1993,
49,
92.
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Secondary reference #2
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Title
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Human carbonic anhydrase i - Iodide complex: structure and inhibition mechanism
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Authors
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V.Kumar,
P.Satyamurthy,
K.K.Kannan.
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Ref.
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acta crystallogr ,sect a, 1987,
43,
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