1hec
From Proteopedia
(New page: 200px<br /> <applet load="1hec" size="450" color="white" frame="true" align="right" spinBox="true" caption="1hec, resolution 2.0Å" /> '''STRUCTURAL CONSEQUEN...) |
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caption="1hec, resolution 2.0Å" /> | caption="1hec, resolution 2.0Å" /> | ||
'''STRUCTURAL CONSEQUENCES OF HYDROPHILIC AMINO-ACID SUBSTITUTIONS IN THE HYDROPHOBIC POCKET OF HUMAN CARBONIC ANHYDRASE II'''<br /> | '''STRUCTURAL CONSEQUENCES OF HYDROPHILIC AMINO-ACID SUBSTITUTIONS IN THE HYDROPHOBIC POCKET OF HUMAN CARBONIC ANHYDRASE II'''<br /> | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1HEC is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with ZN as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Carbonate_dehydratase Carbonate dehydratase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.1.1 4.2.1.1] Full crystallographic information is available from [http:// | + | 1HEC is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=ZN:'>ZN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Carbonate_dehydratase Carbonate dehydratase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.1.1 4.2.1.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1HEC OCA]. |
==Reference== | ==Reference== | ||
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[[Category: lyase(oxo-acid)]] | [[Category: lyase(oxo-acid)]] | ||
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Revision as of 13:56, 15 February 2008
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STRUCTURAL CONSEQUENCES OF HYDROPHILIC AMINO-ACID SUBSTITUTIONS IN THE HYDROPHOBIC POCKET OF HUMAN CARBONIC ANHYDRASE II
Contents |
Overview
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)
Disease
Known disease associated with this structure: Osteopetrosis, autosomal recessive 3, with renal tubular acidosis OMIM:[611492]
About this Structure
1HEC is a Single protein structure of sequence from Homo sapiens with as ligand. Active as Carbonate dehydratase, with EC number 4.2.1.1 Full crystallographic information is available from OCA.
Reference
Structural consequences of hydrophilic amino acid substitutions in the hydrophobic pocket of human carbonic anhydrase II., Nair SK, Christianson DW, Biochemistry. 1993 May 4;32(17):4506-14. PMID:8485129
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