Triose Phosphate Isomerase
From Proteopedia
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=== Acid Base Catalysis === | === Acid Base Catalysis === | ||
| - | TPI carries out the isomerization reaction through acid base chemistry involving <scene name='Triose_Phosphate_Isomerase/Catalytic_residues_with_pga/1'>two catalytic residues</scene>. These two catalytic residues include <scene name='Triose_Phosphate_Isomerase/Glu165/1'>Glutamate 165</scene> which plays the role of the general base catalyst in a proton abstraction mechanism as it abstracts a proton from carbon 1, | + | TPI carries out the isomerization reaction through acid base chemistry involving <scene name='Triose_Phosphate_Isomerase/Catalytic_residues_with_pga/1'>two catalytic residues</scene>. These two catalytic residues include <scene name='Triose_Phosphate_Isomerase/Glu165/1'>Glutamate 165</scene> which plays the role of the general base catalyst in a proton abstraction mechanism as it abstracts a proton from carbon 1, which then donates it to carbon 2. Glutamate 165 requires <scene name='Triose_Phosphate_Isomerase/His95/3'>Histidine 95</scene>, the general acid which donates a proton to the C-1 carbonyl oxygen. |
== Structure & Function == | == Structure & Function == | ||
| - | Triose Phosphate Isomerase is a dimeric protein of two identical subunits. Each subunit contains 8 alpha helices <scene name='Triose_Phosphate_Isomerase/Helices/1'>8 exterior helices</scene> surrounding 8 interior <scene name='Triose_Phosphate_Isomerase/Beta_sheet/1'>beta sheets</scene>, which form | + | Triose Phosphate Isomerase is a dimeric protein of two identical subunits. Each subunit contains 8 alpha helices <scene name='Triose_Phosphate_Isomerase/Helices/1'>8 exterior helices</scene> surrounding 8 interior <scene name='Triose_Phosphate_Isomerase/Beta_sheet/1'>beta sheets</scene>, which form a structural motif called an alpha/beta barrel or <scene name='Triose_Phosphate_Isomerase/Tim_barrel/1'>TIM barrels</scene>, which also contain the catalytic residues. |
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== Disease == | == Disease == | ||
Revision as of 18:46, 21 March 2009
Contents |
Overview
Triose Phosphate Isomerase (TPI or TIM) catalyzes the reversible interconversion of the triose phosphate isomers dihydroxyacetone phosphate (DHAP) and D-glyceraldehyde-3-phosphate(GAP), an essential process in the glycolytic pathway. More simply, the enzyme catalyzes the isomerization of a ketose (DHAP) to an aldose (GAP).
Mechanism
TPI catalyzes the transfer of a hydrogen atom from carbon 1 to carbon 2, an intramolecular oxidation-reduction. This isomerization of a ketose to an aldose proceeds through an enediol intermediate.<Biochemistry 6th Edition>
Acid Base Catalysis
TPI carries out the isomerization reaction through acid base chemistry involving . These two catalytic residues include which plays the role of the general base catalyst in a proton abstraction mechanism as it abstracts a proton from carbon 1, which then donates it to carbon 2. Glutamate 165 requires , the general acid which donates a proton to the C-1 carbonyl oxygen.
Structure & Function
Triose Phosphate Isomerase is a dimeric protein of two identical subunits. Each subunit contains 8 alpha helices surrounding 8 interior , which form a structural motif called an alpha/beta barrel or , which also contain the catalytic residues.
Disease
Triose Phosphate Isomerase Deficiency
TPI deficiency has been most closely linked to a point mutation at the residue which results in the Glu104Asp mutation. A common marker for TPI deficiency is the increased accumulation of dihydroxyacetone phosphate in erythrocyte extracts as a result in the inability of the mutant enzyme to catalyze the isomerization to D-glyceraldehyde-3-phosphate.
References
Triose Phosphate Isomerase [[1]] Triose Phosphate Isomerase Deficiency [[2]]
Proteopedia Page Contributors and Editors (what is this?)
Gregg Snider, Eric Martz, Michal Harel, Alexander Berchansky, David Canner, Eran Hodis, Stephen Everse, Angel Herraez, Jane S. Richardson
