Isoprenoids
| Head and tail position for isoprene |
|---|
 Isoprene |
Isoprenoids are organic compounds that can be derived from isoprene . These include many natural substances that are grouped together to form isoprenoid natural substances . They belong to the group of lipids .
properties
Important subgroups of the isoprenoids are the terpenes and terpenoids , including the steroids . The direct precursor and starting point of the biosynthesis of isoprenoids is not isoprene, but the biochemically activated isopentenyl pyrophosphate (IPP) and its isomer dimethylallyl pyrophosphate (DMAPP). Isoprene itself is produced by many trees and phytoplankton ; the reason for this is not clear. According to one hypothesis, the gaseous isoprene is supposed to protect the plants from oxidation by ground-level ozone . The eponymous structural unit of isoprene is divided into head and tail in terms of orientation. As a donkey bridge , an analogy to a horse can be drawn when depicting isoprene with its head and tail. Naturally occurring polymeric isoprenoids are e.g. B. latex ( cis configuration) or gutta-percha ( trans configuration). A synthetic polymeric isoprenoid is the plastic neoprene .
Isoprenoids are in the environment difficult to degrade as they due to the side chains of microorganisms are difficult to attack, and chemical reactants. Isoprenoids such as pristan are often used as indicators for the age of mixtures of substances or their degradation period in the environment. The ratio of pristane to the other components increases with increasing duration.
biosynthesis
There are two metabolic pathways in nature that lead to the production of isoprenoids, the mevalonate path (synonymous with MVA pathway) and the DOXP pathway (synonymous with MEP pathway). The mevalonate pathway used as starting material mevalonate and as a typical enzyme , the HMG-CoA reductase , while the DOXP pathway of 1-deoxy-D-xylulose-5-phosphate originates and as a typical enzyme, the 1-deoxy-D-xylulose-5- phosphate synthase used.
| organism | Metabolic pathway |
|---|---|
| bacteria | MVA or MEP |
| Archaea | MVA |
| Green algae | MEP |
| plants | MVA and MEP |
| Animals | MVA |
| Mushrooms | MVA |
literature
- Otto Wolfgang Thiele: Lipids, isoprenoids with steroids . Georg Thieme Verlag, Stuttgart 1979, ISBN 3-13-576301-3 .
- Finian J. Leeper (Ed.), John C. Vederas (Ed.): Biosynthesis: Aromatic Polyketides, Isoprenoids, Alkaloids . 1st edition. Springer Verlag, Heidelberg / Berlin 2007, ISBN 3-540-66573-0 .
Web links
Individual evidence
- ^ Peter Nuhn: Naturstoffchemie , 2nd edition, S. Hirzel Wissenschaftliche Verlagsgesellschaft, Stuttgart 1990, ISBN 3-7776-0473-9 , pp. 466-519.
- ↑ Helmut Kindl: Biochemistry of Plants. Springer-Verlag, 2013, ISBN 978-3-662-06055-1 , p. 209.