Epämevalonaattipolku

Epämevalonaattipolku, also known as the non-mevalonate pathway or MEP pathway, is a crucial metabolic route found in bacteria, algae, apicomplexan parasites, and some plant tissues. This pathway is responsible for the biosynthesis of isoprenoids, a diverse class of organic compounds essential for various biological functions. Isoprenoids play roles as building blocks for molecules like carotenoids, essential components of photosynthesis, and hormones such as gibberellins in plants.

The MEP pathway begins with the condensation of pyruvate and glyceraldehyde-3-phosphate, forming 1-deoxy-D-xylulose-5-phosphate (DXP). This initial step is catalyzed by the enzyme DXP synthase. Through a series of subsequent enzymatic reactions, including reductions and isomerizations, DXP is converted into isopentenyl pyrophosphate (IPP) and its isomer dimethylallyl pyrophosphate (DMAPP). These two five-carbon molecules, IPP and DMAPP, are the fundamental building blocks of all isoprenoids. They can then be sequentially condensed to form longer isoprenoid chains, leading to the synthesis of a vast array of compounds.

The MEP pathway is distinct from the mevalonate pathway (MVA pathway), which serves a similar isoprenoid-producing function but is primarily found in archaea, fungi, and animals. The presence of the MEP pathway in various organisms highlights its evolutionary significance in providing essential compounds for life. In some organisms, both pathways can coexist, contributing to a broader spectrum of isoprenoid production. Research into the MEP pathway is ongoing, with potential applications in drug development, particularly against pathogens that rely on this pathway for survival.