1TPH

Triosephosphate isomerase (TIM) is one of the most extensively characterised enzymes in the chemical literature. TIM is a glycolytic enzyme that catalyses the central reaction in the glycolytic pathway, the interconversion of D-glyceraldehyde 3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP) with exceptionally high efficiency, while suppressing elimination of orthophosphate. It contains a large-scale catalytic loop motion, which alternates in open and closed positions. It is a homodimer and only the homodimer is fully active. TIM is known to exist in an unliganded and liganded conformation and the loop-6, in particular, would undergo the major conformational changes when there is a substrate or inhibitor bound at the active site. In addition, the shift of loop-6 preferentially stabilises the enediole phosphate intermediate.

Its deficiency has been shown to enhance levels of dihydroxyacetone phosphate in humans and cause chronic anaemia and neuromuscular impairment. Due to its important place in glycolysis, TIM also forms an attractive target for drug design against parasites that have the ability to survive in the mammalian bloodstream. Among the various diseases currently ravaging the tropical world, those due to such parasites are some of the most serious ones (e.g., malaria and sleeping sickness). Control of these diseases is presently a major problem and has been a focus of attention of various agencies.