|
|
| Line 1: |
Line 1: |
| [[Image:1pa1.jpg|left|200px]] | | {{Seed}} |
| | [[Image:1pa1.png|left|200px]] |
|
| |
|
| <!-- | | <!-- |
| Line 9: |
Line 10: |
| {{STRUCTURE_1pa1| PDB=1pa1 | SCENE= }} | | {{STRUCTURE_1pa1| PDB=1pa1 | SCENE= }} |
|
| |
|
| '''Crystal structure of the C215D mutant of protein tyrosine phosphatase 1B'''
| | ===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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_12748196}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 12748196 is the PubMed ID number. |
| | --> |
| | {{ABSTRACT_PUBMED_12748196}} |
|
| |
|
| ==About this Structure== | | ==About this Structure== |
| Line 33: |
Line 37: |
| [[Category: Catalytic loop]] | | [[Category: Catalytic loop]] |
| [[Category: Phosphatase]] | | [[Category: Phosphatase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 04:52:17 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 15:49:28 2008'' |
