Triose Phosphate Isomerase: Difference between revisions

'''Triose Phosphate Isomerase''' (TPI or TIM) [5.3.1.1] is a ubiquitous enzyme with a molecular weight of roughly 54 kD (27 kD per subunit) which catalyzes the reversible interconversion of the triose phosphate isomers dihydroxyacetone phosphate ([http://en.wikipedia.org/wiki/DHAP DHAP]) and D-glyceraldehyde-3-phosphate <scene name='Triose_Phosphate_Isomerase/Pga/1'>(GAP)</scene>, an essential process in the glycolytic pathway. More simply, the enzyme catalyzes the [http://en.wikipedia.org/wiki/Isomerization isomerization] of a ketose (DHAP) to an aldose [http://en.wikipedia.org/wiki/Glyceraldehyde_3-phosphate GAP] also referred to as PGAL. In regards to the two isomers, at equilibrium, roughly 96% of the triose phosphate is in the DHAP isomer form; however, the isomerization reaction proceeds due to the rapid removal of GAP from the subsequent reactions of [http://en.wikipedia.org/wiki/Glycolysis glycolysis]. TPI is an example of a [http://en.wikipedia.org/wiki/Catalytically_perfect_enzyme catalytically perfect enzyme], indicating that for almost every enzyme-substrate encounter, a product is formed and that this interaction is only limited by the substrate diffusion rate. Other catalytically perfect enzymes include [http://en.wikipedia.org/wiki/Carbonic_anhydrase carbonic anhydrase], [http://en.wikipedia.org/wiki/Acetylcholinesterase acetylcholinesterase], [http://en.wikipedia.org/wiki/Catalase catalase] and [http://en.wikipedia.org/wiki/Fumarase fumarase]. In addition to its relevance in glycolysis, TPI is also involved in several additional metabolic biological processes including gluconeogenesis, the pentose phosphate shunt and fatty acid biosynthesis.