Terpénoïde

The terpénoïdes , that one calls sometimes isoprénoïdes , form a broad and various class organic compounds which one meets in nature, similar to the Terpène S, drifting of units Isoprène with five carbons assembled and modified thousands in ways.

The majority of these compounds have multicyclic structures which different from/to each other not only by the functional groups, but also by the basic structure of their hydrocarbon skeletons. These Lipide S can be found in all the classes of alive creatures, and sets up the broadest group of natural products.

The terpénoïdes of plants are used much because of their aromatic qualities. They play a part in the remedies in traditional herb trade and are the subject of research to discover effects Antibactérien S, Antinéoplastique S or other effects Pharmaceutique S.

The terpénoïdes contribute to the perfume of the Eucalyptus, with the taste of the grooves, of the Clove and the Gingembre and with the yellow colors of the flowers. Among the known terpénoïdes one can quote the Citral, the Menthol, the Camphre and the Cannabinoïde S found in the plant of Cannabis .

The Steroid S and the Stérol S in the animals are produced biologically starting from precursors terpénoïdes. The connection of Protéine S with terpénoïdes causes to increase their attachment with the cellular Membrane; this post-traductionnelle Modification is called the Isoprénylation.

Structure and classification

The Terpène S are Hydrocarbure S resulting from the combination of several units Isoprène. The terpénoïdes can be regarded as modified terpenes, with groups Méthyle S added or removed, or atoms of added Oxygène (certain authors use the " term; terpène" in a broader way, by including the terpénoides there). Just like terpenes, the terpénoïdes can be classified according to their number of units isoprene:
  • Monoterpénoïdes, 2 units isoprene,
  • Sesquiterpénoïdes, 3 units isoprene,
  • Diterpénoïdes, 4 units isoprene,
  • Sesterterpénoïdes, 5 units isoprene,
  • Triterpénoïdes, 6 units isoprene,
  • Tetraterpénoïdes, 8 units isoprene,
  • Polyterpénoïdes with a more significant number of units isoprene,
The terpénoïdes can also be classified according to the number of cyclic structures which they contain.

Biosynthesis

There are two metabolic ways synthesis of the terpénoïdes:

Chemin de l' mevalonic acid

Many organizations produce terpénoïdes via the way of the HMG-CoA réductase, or way of the Mevalonic acid , which also leads to the Cholestérol. The reactions take place in the Cytoplasme. The way was discovered in the years 1950.

Chemin MEP /DOXP

The way of the 2 - C - methyl-D-ÉRYTHRITOl 4-phosphate/1-déoxy-D-xylulose 5-phosphate (MEP/DOXP), also called way Non-mévalonate or way independent of the Mevalonic acid , is held in the Chloroplaste S of the plants, in the protozoa Apicomplexien S and at much of Bactérie S. He was discovered at the end of the years 1980.

The Pyruvate and the Glycéraldéhyde-3-phosphate are converted by the DOXP synthase (Dxs) into 1-déoxy-D-xylulose 5-phosphate, and by the DOXP réductase (Dxr, IspC) in 2 - C - methyl-D-ÉRYTHRITOl 4-phosphate (MEP). The three subsequent reactional stages catalyzed by the 4-diphosphocytidyl-2- C - methyl-D-ÉRYTHRITOl synthase (YgbP, IspD), the 4-diphosphocytidyl-2- C - methyl-D-ÉRYTHRITOl kinase (YchB, IspE), and the 2 - C - methyl-D-ÉRYTHRITOl 2,4-cyclodiphosphate synthase (YgbB, IspF) médient the formation of 2 - C - methyl-D-ÉRYTHRITOl 2,4-cyclopyrophosphate (MEcPP). Finally, MEcPP is converted into ( E ) - 4-hydroxy-3-methyl-goal-2-ényl pyrophosphate (HMB-PP) by the HMB-PP synthase (GcpE, IspG), and the HMB-PP is converted into Isopentényl pyrophosphate (IPP) and into Diméthylallyl pyrophosphate (DMAPP) by the HMB-PP réductase (LytB, IspH).

End products

The IPP and the DMAPP are the end products in the two metabolic ways, and are the precursors of the Isoprène, of the monoterpénoïdes (molecule with 10 carbons), of the diterpénoïdes (20 carbons), of the Caroténoïde S (40 carbons), of the Chlorophylle S and the Plastoquinone -9 (45 carbons). The synthesis of all the Terpénoïde S of higher molecular weight occurs via the formation from géranyl pyrophosphate (GPP), from Farnésyl pyrophosphate (FP), and from Géranylgéranyl pyrophosphate (GGPP).

Although the two metabolic ways (Mva and MEP) are mutually exclusive at the majority of the organizations, of the interactions between them were updated at the Plante S and some species of Bactérie S.

See too

External bond

  • Nomenclature IUPAC of the terpénoïdes

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