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PDBsum entry 3ks3

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Lyase PDB id
3ks3
Jmol
Contents
Protein chain
257 a.a.
Ligands
GOL
Metals
_ZN
Waters ×483

References listed in PDB file
Key reference
Title A short, Strong hydrogen bond in the active site of human carbonic anhydrase ii.
Authors B.S.Avvaru, C.U.Kim, K.H.Sippel, S.M.Gruner, M.Agbandje-Mckenna, D.N.Silverman, R.Mckenna.
Ref. Biochemistry, 2010, 49, 249-251.
PubMed id 20000378
Abstract
The crystal structure of human carbonic anhydrase II (HCA II) obtained at 0.9 A resolution reveals that a water molecule, termed deep water, Dw, and bound in a hydrophobic pocket of the active site forms a short, strong hydrogen bond with the zinc-bound solvent molecule, a conclusion based on the observed oxygen-oxygen distance of 2.45 A. This water structure has similarities with hydrated hydroxide found in crystals of certain inorganic complexes. The energy required to displace Dw contributes in significant part to the weak binding of CO(2) in the enzyme-substrate complex, a weak binding that enhances k(cat) for the conversion of CO(2) into bicarbonate. In addition, this short, strong hydrogen bond is expected to contribute to the low pK(a) of the zinc-bound water and to promote proton transfer in catalysis.
PROCHECK
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 Headers