1alh
From Proteopedia
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| - | [[Image:1alh.gif|left|200px]] | + | [[Image:1alh.gif|left|200px]] |
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| - | '''KINETICS AND CRYSTAL STRUCTURE OF A MUTANT E. COLI ALKALINE PHOSPHATASE (ASP-369-->ASN): A MECHANISM INVOLVING ONE ZINC PER ACTIVE SITE''' | + | {{Structure |
| + | |PDB= 1alh |SIZE=350|CAPTION= <scene name='initialview01'>1alh</scene>, resolution 2.5Å | ||
| + | |SITE= | ||
| + | |LIGAND= <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene>, <scene name='pdbligand=PO4:PHOSPHATE+ION'>PO4</scene> and <scene name='pdbligand=SO4:SULFATE ION'>SO4</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] | ||
| + | |GENE= PHOA ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli]) | ||
| + | }} | ||
| + | |||
| + | '''KINETICS AND CRYSTAL STRUCTURE OF A MUTANT E. COLI ALKALINE PHOSPHATASE (ASP-369-->ASN): A MECHANISM INVOLVING ONE ZINC PER ACTIVE SITE''' | ||
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==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1ALH is a [ | + | 1ALH is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ALH OCA]. |
==Reference== | ==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:[http:// | + | 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:[http://www.ncbi.nlm.nih.gov/pubmed/7703848 7703848] |
[[Category: Alkaline phosphatase]] | [[Category: Alkaline phosphatase]] | ||
[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
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[[Category: hydrolase (phosphoric monoester)]] | [[Category: hydrolase (phosphoric monoester)]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 09:59:13 2008'' |
Revision as of 07:59, 20 March 2008
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| , resolution 2.5Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | , and | ||||||
| Gene: | PHOA (Escherichia coli) | ||||||
| Activity: | Alkaline phosphatase, with EC number 3.1.3.1 | ||||||
| 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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