1alh
From Proteopedia
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|PDB= 1alh |SIZE=350|CAPTION= <scene name='initialview01'>1alh</scene>, resolution 2.5Å | |PDB= 1alh |SIZE=350|CAPTION= <scene name='initialview01'>1alh</scene>, resolution 2.5Å | ||
|SITE= | |SITE= | ||
| - | |LIGAND= <scene name='pdbligand= | + | |LIGAND= <scene name='pdbligand=PO4:PHOSPHATE+ION'>PO4</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene> |
| - | |ACTIVITY= [http://en.wikipedia.org/wiki/Alkaline_phosphatase Alkaline phosphatase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.3.1 3.1.3.1] | + | |ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Alkaline_phosphatase Alkaline phosphatase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.3.1 3.1.3.1] </span> |
|GENE= PHOA ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli]) | |GENE= PHOA ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli]) | ||
| + | |DOMAIN= | ||
| + | |RELATEDENTRY= | ||
| + | |RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1alh FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1alh OCA], [http://www.ebi.ac.uk/pdbsum/1alh PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1alh RCSB]</span> | ||
}} | }} | ||
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[[Category: Tibbitts, T T.]] | [[Category: Tibbitts, T T.]] | ||
[[Category: Xu, X.]] | [[Category: Xu, X.]] | ||
| - | [[Category: PO4]] | ||
| - | [[Category: SO4]] | ||
| - | [[Category: ZN]] | ||
[[Category: hydrolase (phosphoric monoester)]] | [[Category: hydrolase (phosphoric monoester)]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 18:42:48 2008'' |
Revision as of 15:42, 30 March 2008
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| , resolution 2.5Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | , , | ||||||
| Gene: | PHOA (Escherichia coli) | ||||||
| Activity: | Alkaline phosphatase, with EC number 3.1.3.1 | ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
KINETICS AND CRYSTAL STRUCTURE OF A MUTANT E. COLI ALKALINE PHOSPHATASE (ASP-369-->ASN): A MECHANISM INVOLVING ONE ZINC PER ACTIVE SITE
Overview
Using site-directed mutagenesis, an aspartate side chain involved in binding metal ions in the active site of Escherichia coli alkaline phosphatase (Asp-369) was replaced, alternately, by asparagine (D369N) and by alanine (D369A). The purified mutant enzymes showed reduced turnover rates (kcat) and increased Michaelis constants (Km). The kcat for the D369A enzyme was 5,000-fold lower than the value for the wild-type enzyme. The D369N enzyme required Zn2+ in millimolar concentrations to become fully active; even under these conditions the kcat measured for hydrolysis of p-nitrophenol phosphate was 2 orders of magnitude lower than for the wild-type enzyme. Thus the kcat/Km ratios showed that catalysis is 50 times less efficient when the carboxylate side chain of Asp-369 is replaced by the corresponding amide; and activity is reduced to near nonenzymic levels when the carboxylate is replaced by a methyl group. The crystal structure of D369N, solved to 2.5 A resolution with an R-factor of 0.189, showed vacancies at 2 of the 3 metal binding sites. On the basis of the kinetic results and the refined X-ray coordinates, a reaction mechanism is proposed for phosphate ester hydrolysis by the D369N enzyme involving only 1 metal with the possible assistance of a histidine side chain.
About this Structure
1ALH is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Kinetics and crystal structure of a mutant Escherichia coli alkaline phosphatase (Asp-369-->Asn): a mechanism involving one zinc per active site., Tibbitts TT, Xu X, Kantrowitz ER, Protein Sci. 1994 Nov;3(11):2005-14. PMID:7703848
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