Triose Phosphate Isomerase Structure & Mechanism
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| - | Triose phosphate isomerase (TIM) is a crucial enzyme in the glycolytic pathway. TIM reversibly converts the aldose Glyceraldehyde-3-phosphate (GASP) to the ketose Dihydroxyacetone phosphate (DHAP). The interconversion proceeds by an enediol intermediate. | + | Triose phosphate isomerase (TIM) is a crucial enzyme in the glycolytic pathway. <scene name='Christian_Krenk_Sandbox/Nc_rainbow/1'>TIM</scene> reversibly converts the aldose Glyceraldehyde-3-phosphate (GASP) to the ketose Dihydroxyacetone phosphate (DHAP). The interconversion proceeds by an enediol intermediate. |
==Structural Characteristics of TIM== | ==Structural Characteristics of TIM== | ||
Revision as of 13:58, 1 March 2010
Triose Phosphate Isomerase (TIM)
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Triose phosphate isomerase (TIM) is a crucial enzyme in the glycolytic pathway. reversibly converts the aldose Glyceraldehyde-3-phosphate (GASP) to the ketose Dihydroxyacetone phosphate (DHAP). The interconversion proceeds by an enediol intermediate.
Structural Characteristics of TIM
Secondary Structure: Alpha helices and Beta sheets Tertiary Structure: Alpha/Beta barrel Quaternary Structure: Homodimer
Mechanism of TIM
The enzyme aids in catalysis by binding tightly to the enediol transition state. To convert GAP to the enediol intermediate, a proton is abstracted from C2 by a base and the carbonyl oxygen atom is protonated by an acid. TIM’s Glu 165 acts as the base and grabs GAP’s C2 proton, while His 95 is H-bonded to the carbonyl oxygen and acts as the acid by protonating carbonyl oxygen. The enediol intermediate is negatively charged, but is somewhat stabilized by Lys 12’s positively charged side chain. To convert the enediol intermediate to DHAP, C1 is protonated by Glu 165, with His 95 removing a proton from C2’s OH group. As a result, the catalytic groups are back at their original states, and catalysis is completed.
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| 1wyi, resolution 2.20Å () | |||||||||
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| Activity: | Triose-phosphate isomerase, with EC number 5.3.1.1 | ||||||||
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| Resources: | FirstGlance, OCA, RCSB, PDBsum | ||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||
Proteopedia Page Contributors and Editors (what is this?)
Christian Krenk, Alexander Berchansky, Diamond B. Reese, Michal Harel, Jane S. Richardson, David Canner
