User:Eran Hodis/Sandbox3
From Proteopedia
Overview
Triose Phosphate Isomerase (TPI or TIM)is a ubiquitous enzyme with a molecular weight of 56 kD which catalyzes the reversible interconversion of the triose phosphate isomers dihydroxyacetone phosphate (DHAP) and D-glyceraldehyde-3-phosphate , an essential process in the glycolytic pathway. More simply, the enzyme catalyzes the isomerization of a ketose (DHAP) to an aldose 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 glycolysis. TPI is an example of a 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 carbonic anhydrase, acetylcholinesterase, catalase and fumarase. In addition to its relevance in glycolysis, TPI is also involved in metabolic biological processes such as gluconeogenesis, pentose phosphate shunt and fatty acid biosynthesis among others.
