1pa1
From Proteopedia
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|PDB= 1pa1 |SIZE=350|CAPTION= <scene name='initialview01'>1pa1</scene>, resolution 1.6Å | |PDB= 1pa1 |SIZE=350|CAPTION= <scene name='initialview01'>1pa1</scene>, resolution 1.6Å | ||
|SITE= | |SITE= | ||
| - | |LIGAND= <scene name='pdbligand= | + | |LIGAND= <scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene> |
| - | |ACTIVITY= [http://en.wikipedia.org/wiki/Protein-tyrosine-phosphatase Protein-tyrosine-phosphatase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.3.48 3.1.3.48] | + | |ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Protein-tyrosine-phosphatase Protein-tyrosine-phosphatase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.3.48 3.1.3.48] </span> |
|GENE= | |GENE= | ||
| + | |DOMAIN= | ||
| + | |RELATEDENTRY= | ||
| + | |RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1pa1 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1pa1 OCA], [http://www.ebi.ac.uk/pdbsum/1pa1 PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1pa1 RCSB]</span> | ||
}} | }} | ||
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==Overview== | ==Overview== | ||
We have characterized the C215D active-site mutant of protein-tyrosine phosphatase-1B (PTP-1B) and solved the crystal structure of the catalytic domain of the apoenzyme to a resolution of 1.6 A. The mutant enzyme displayed maximal catalytic activity at pH approximately 4.5, which is significantly lower than the pH optimum of 6 for wild-type PTP-1B. Although both forms of the enzyme exhibited identical Km values for hydrolysis of p-nitrophenyl phosphate at pH 4.5 and 6, the kcat values of C215D were approximately 70- and approximately 7000-fold lower than those of wild-type PTP-1B, respectively. Arrhenius plots revealed that the mutant and wild-type enzymes displayed activation energies of 61 +/- 1 and 18 +/- 2 kJ/mol, respectively, at their pH optima. Unlike wild-type PTP-1B, C215D-mediated p-nitrophenyl phosphate hydrolysis was inactivated by 1,2-epoxy-3-(p-nitrophenoxy)propane, suggesting a direct involvement of Asp215 in catalysis. Increasing solvent microviscosity with sucrose (up to 40% (w/v)) caused a significant decrease in kcat/Km of the wild-type enzyme, but did not alter the catalytic efficiency of the mutant protein. Structurally, the apoenzyme was identical to wild-type PTP-1B, aside from the flexible WPD loop region, which was in both "open" and "closed" conformations. At physiological pH, the C215D mutant of PTP-1B should be an effective substrate-trapping mutant that can be used to identify cellular substrates of PTP-1B. In addition, because of its insensitivity to oxidation, this mutant may be used for screening fermentation broth and other natural products to identify inhibitors of PTP-1B. | We have characterized the C215D active-site mutant of protein-tyrosine phosphatase-1B (PTP-1B) and solved the crystal structure of the catalytic domain of the apoenzyme to a resolution of 1.6 A. The mutant enzyme displayed maximal catalytic activity at pH approximately 4.5, which is significantly lower than the pH optimum of 6 for wild-type PTP-1B. Although both forms of the enzyme exhibited identical Km values for hydrolysis of p-nitrophenyl phosphate at pH 4.5 and 6, the kcat values of C215D were approximately 70- and approximately 7000-fold lower than those of wild-type PTP-1B, respectively. Arrhenius plots revealed that the mutant and wild-type enzymes displayed activation energies of 61 +/- 1 and 18 +/- 2 kJ/mol, respectively, at their pH optima. Unlike wild-type PTP-1B, C215D-mediated p-nitrophenyl phosphate hydrolysis was inactivated by 1,2-epoxy-3-(p-nitrophenoxy)propane, suggesting a direct involvement of Asp215 in catalysis. Increasing solvent microviscosity with sucrose (up to 40% (w/v)) caused a significant decrease in kcat/Km of the wild-type enzyme, but did not alter the catalytic efficiency of the mutant protein. Structurally, the apoenzyme was identical to wild-type PTP-1B, aside from the flexible WPD loop region, which was in both "open" and "closed" conformations. At physiological pH, the C215D mutant of PTP-1B should be an effective substrate-trapping mutant that can be used to identify cellular substrates of PTP-1B. In addition, because of its insensitivity to oxidation, this mutant may be used for screening fermentation broth and other natural products to identify inhibitors of PTP-1B. | ||
| - | |||
| - | ==Disease== | ||
| - | Known diseases associated with this structure: Abdominal body fat distribution, modifier of OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=176885 176885]], Insulin resistance, susceptibility to OMIM:[[http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=176885 176885]] | ||
==About this Structure== | ==About this Structure== | ||
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[[Category: Romsicki, Y.]] | [[Category: Romsicki, Y.]] | ||
[[Category: Scapin, G.]] | [[Category: Scapin, G.]] | ||
| - | [[Category: CL]] | ||
| - | [[Category: MG]] | ||
[[Category: active-site mutant]] | [[Category: active-site mutant]] | ||
[[Category: catalytic loop]] | [[Category: catalytic loop]] | ||
[[Category: phosphatase]] | [[Category: phosphatase]] | ||
| - | ''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 22:57:02 2008'' |
Revision as of 19:57, 30 March 2008
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| , resolution 1.6Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | , | ||||||
| Activity: | Protein-tyrosine-phosphatase, with EC number 3.1.3.48 | ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Crystal structure of the C215D mutant of protein tyrosine phosphatase 1B
Overview
We have characterized the C215D active-site mutant of protein-tyrosine phosphatase-1B (PTP-1B) and solved the crystal structure of the catalytic domain of the apoenzyme to a resolution of 1.6 A. The mutant enzyme displayed maximal catalytic activity at pH approximately 4.5, which is significantly lower than the pH optimum of 6 for wild-type PTP-1B. Although both forms of the enzyme exhibited identical Km values for hydrolysis of p-nitrophenyl phosphate at pH 4.5 and 6, the kcat values of C215D were approximately 70- and approximately 7000-fold lower than those of wild-type PTP-1B, respectively. Arrhenius plots revealed that the mutant and wild-type enzymes displayed activation energies of 61 +/- 1 and 18 +/- 2 kJ/mol, respectively, at their pH optima. Unlike wild-type PTP-1B, C215D-mediated p-nitrophenyl phosphate hydrolysis was inactivated by 1,2-epoxy-3-(p-nitrophenoxy)propane, suggesting a direct involvement of Asp215 in catalysis. Increasing solvent microviscosity with sucrose (up to 40% (w/v)) caused a significant decrease in kcat/Km of the wild-type enzyme, but did not alter the catalytic efficiency of the mutant protein. Structurally, the apoenzyme was identical to wild-type PTP-1B, aside from the flexible WPD loop region, which was in both "open" and "closed" conformations. At physiological pH, the C215D mutant of PTP-1B should be an effective substrate-trapping mutant that can be used to identify cellular substrates of PTP-1B. In addition, because of its insensitivity to oxidation, this mutant may be used for screening fermentation broth and other natural products to identify inhibitors of PTP-1B.
About this Structure
1PA1 is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Functional characterization and crystal structure of the C215D mutant of protein-tyrosine phosphatase-1B., Romsicki Y, Scapin G, Beaulieu-Audy V, Patel S, Becker JW, Kennedy BP, Asante-Appiah E, J Biol Chem. 2003 Aug 1;278(31):29009-15. Epub 2003 May 13. PMID:12748196
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