Triose Phosphate Isomerase Structure & Mechanism
Triose Phosphate Isomerase (TIM)Triose Phosphate Isomerase (TIM)
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Triose phosphate isomerase (TIM)[1] (PDB 1wyi) 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 TIMStructural Characteristics of TIM
The secondary structure consists of 14 alpha helices and 8 beta sheets per monomer. Alpha/Beta barrel Quaternary Structure: Homodimer
Mechanism of TIMMechanism 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 | ||||||||
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| 1hti, resolution 2.80Å () | |||||||||
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| Ligands: | |||||||||
| 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 | ||||||||
ReferencesReferences
- ↑ Kinoshita T, Maruki R, Warizaya M, Nakajima H, Nishimura S. Structure of a high-resolution crystal form of human triosephosphate isomerase: improvement of crystals using the gel-tube method. Acta Crystallogr Sect F Struct Biol Cryst Commun. 2005 Apr 1;61(Pt, 4):346-9. Epub 2005 Mar 24. PMID:16511037 doi:10.1107/S1744309105008341