triose-phosphate isomerase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: D-glyceraldehyde 3-phosphate = glycerone phosphate. [EC:5.3.1.1, RHEA:18585]

Triose-phosphate isomerase (TIM) activity catalyzes the reversible interconversion of dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP), two key intermediates in glycolysis and gluconeogenesis. The enzyme employs a two-step mechanism involving the abstraction of a proton from the C-2 hydroxyl group of DHAP, forming an enediol intermediate. This intermediate is then reprotonated at the C-1 position, yielding GAP. This reaction is essential for maintaining a balanced supply of GAP for the subsequent steps of glycolysis and gluconeogenesis. TIM is highly efficient, with a catalytic rate constant (kcat) in the range of 10^5 to 10^6 s-1, indicating that the enzyme can convert thousands of substrate molecules per second. The active site of TIM is highly conserved across different species and contains two catalytic residues, Glu165 and Lys13. Glu165 acts as a general base to abstract the proton from the C-2 hydroxyl group of DHAP, while Lys13 stabilizes the enediol intermediate. TIM is a homodimer, with each monomer consisting of two domains: a large, open "barrel" domain and a smaller, closed "lid" domain. The active site is located at the interface between the two domains. The lid domain plays a crucial role in substrate binding and product release. Mutations in TIM can lead to various diseases, including hemolytic anemia, neurological disorders, and cancer.'
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Proteins (1)

Compounds (2)