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Interaction between the two metabolic pathways can be studied by using 13 C-glucose isotopomers. [10] In higher plants, the MEP pathway operates in plastids while the mevalonate pathway operates in the cytosol. [9] Examples of bacteria that contain the MEP pathway include Escherichia coli and pathogens such as Mycobacterium tuberculosis.
Isoprene is made through the methyl-erythritol 4-phosphate pathway (MEP pathway, also called the non-mevalonate pathway) in the chloroplasts of plants. One of the two end-products of MEP pathway, dimethylallyl pyrophosphate (DMAPP), is cleaved by the enzyme isoprene synthase to form isoprene and diphosphate.
The mevalonate pathway (MVA pathway or HMG-CoA reductase pathway) and the MEP pathway are metabolic pathways for the biosynthesis of isoprenoid precursors: IPP and DMAPP. Whereas plants use both MVA and MEP pathway, most organisms only use one of the pathways for the biosynthesis of isoprenoid precursors.
The color scheme does not correctly represent the origins of the isoprene units of GPP. IPP can be synthesised via an alternative non-mevalonate pathway of isoprenoid precursor biosynthesis, the MEP pathway, where it is formed from -4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMB-PP) by the enzyme HMB-PP reductase (LytB, IspH).
It is a product of both the mevalonate pathway and the MEP pathway of isoprenoid precursor biosynthesis. It is an isomer of isopentenyl pyrophosphate (IPP) and exists in virtually all life forms. The enzyme isopentenyl pyrophosphate isomerase catalyzes isomerization between DMAPP and IPP.
An alternative, unrelated biosynthesis pathway of IPP is known in some bacterial groups and the plastids of plants, the so-called MEP-(2-methyl-D-erythritol-4-phosphate) pathway, which is initiated from C 5 sugars. In both pathways, IPP is isomerized to DMAPP by the enzyme isopentenyl pyrophosphate isomerase.
The terpenoids, also known as isoprenoids, are a class of naturally occurring organic chemicals derived from the 5-carbon compound isoprene and its derivatives called terpenes, diterpenes, etc. While sometimes used interchangeably with "terpenes", terpenoids contain additional functional groups , usually containing oxygen. [ 1 ]
He is known for establishing the non-mevalonate desoxyxylulose-phosphate / methylerythritol phosphate pathway (DOXP / MEP pathway) of isoprenoid biosynthesis in chloroplasts. [3] The latter, which is responsible for the biosynthesis of carotenoids, prenyl-quinones, isoprene, mono- and diterpenes was detected in the 1990s (via 13 C-labelling ...