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PDBsum entry 1hec
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Lyase(oxo-acid)
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PDB id
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1hec
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Contents |
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* Residue conservation analysis
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Enzyme class 2:
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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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Enzyme class 3:
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E.C.4.2.1.69
- cyanamide hydratase.
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Reaction:
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urea = cyanamide + H2O
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urea
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=
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cyanamide
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+
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H2O
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Note, where more than one E.C. class is given (as above), each may
correspond to a different protein domain or, in the case of polyprotein
precursors, to a different mature protein.
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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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Biochemistry
32:4506-4514
(1993)
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PubMed id:
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Structural consequences of hydrophilic amino acid substitutions in the hydrophobic pocket of human carbonic anhydrase II.
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S.K.Nair,
D.W.Christianson.
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ABSTRACT
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The three-dimensional structures of Leu-198-->Glu, Leu-198-->His,
Leu-198-->Arg, and Leu-198-->Ala variants of human carbonic anhydrase II
(CAII) have each been determined by X-ray crystallographic methods to a
resolution of 2.0 A. The side chain of Leu-198 is located at the mouth of the
active site hydrophobic pocket, and this pocket is required for substrate
association. Hydrophobic-->hydrophilic amino acid substitutions at the mouth
of the pocket decrease kcat/KM for CO2 hydration: the CO2 hydrase activities of
Leu-198-->Glu, Leu-198-->His, and Leu-198-->Arg CAIIs are diminished
19-fold, 10-fold, and 17-fold, respectively, relative to the wild-type enzyme;
however, the substitution of a compact aliphatic side chain for Leu-198 has a
smaller effect on catalysis, in that Leu-198-->Ala CAII exhibits only a
3-fold decrease in CO2 hydrase activity [Krebs, J. F., Rana, F., Dluhy, R. A.,
& Fierke, C. A. (1993) Biochemistry (preceding paper in this issue)]. It is
intriguing that CO2 hydrase activity is not severely diminished in
Leu-198-->Arg CAII, even though the side chain of Arg-198 blocks the
hydrophobic pocket. Therefore, the bulky side chain of Arg-198 must be
reasonably mobile in order to accommodate substrate association. Significantly,
a residue larger than the wild-type Leu-198 side chain does not necessarily
block the substrate association pocket; e.g., the side chain of Glu-198 packs
against a hydrophobic patch, the net result of which is a wider mouth for the
pocket.(ABSTRACT TRUNCATED AT 250 WORDS)
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Literature references that cite this PDB file's key reference
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PubMed id
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Reference
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B.Sjöblom,
M.Polentarutti,
and
K.Djinovic-Carugo
(2009).
Structural study of X-ray induced activation of carbonic anhydrase.
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Proc Natl Acad Sci U S A,
106,
10609-10613.
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PDB codes:
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V.M.Krishnamurthy,
G.K.Kaufman,
A.R.Urbach,
I.Gitlin,
K.L.Gudiksen,
D.B.Weibel,
and
G.M.Whitesides
(2008).
Carbonic anhydrase as a model for biophysical and physical-organic studies of proteins and protein-ligand binding.
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Chem Rev,
108,
946.
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S.Huang,
B.Sjöblom,
A.E.Sauer-Eriksson,
and
B.H.Jonsson
(2002).
Organization of an efficient carbonic anhydrase: implications for the mechanism based on structure-function studies of a T199P/C206S mutant.
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Biochemistry,
41,
7628-7635.
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PDB codes:
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D.W.Christianson,
and
J.D.Cox
(1999).
Catalysis by metal-activated hydroxide in zinc and manganese metalloenzymes.
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Annu Rev Biochem,
68,
33-57.
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T.P.Lo,
M.E.Murphy,
J.G.Guillemette,
M.Smith,
and
G.D.Brayer
(1995).
Replacements in a conserved leucine cluster in the hydrophobic heme pocket of cytochrome c.
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Protein Sci,
4,
198-208.
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PDB codes:
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The most recent references are shown first.
Citation data come partly from CiteXplore and partly
from an automated harvesting procedure. Note that this is likely to be
only a partial list as not all journals are covered by
either method. However, we are continually building up the citation data
so more and more references will be included with time.
Where a reference describes a PDB structure, the PDB
codes are
shown on the right.
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Links
