Biosynthesis of carotenoids

摘要: The carotenoids that are found in the photosynthetic pigment-protein complexes of higher plants, algae and phototrophic bacteria, including cyanobacteria, C40 tetraterpenes. They biosynthesised by a specialised branch isoprenoid or terpenoid pathway which is also used for biosynthesis wide variety other important compounds. All compounds built up from C5 “isoprene unit” carbon skeleton clearly seen intermediate isopentenyl diphosphate (IDP). A series intermediates with chains consisting multiples five atoms then this isoprene unit intermediate. In first step process, IDP undergoes double bond isomerisation to give dimethylallyl (DMADP). prenyl transferase enzymes build chain these two intermediates. condensation, between DMADP IDP, gives C10 compound geranyl (GDP), precursor monoterpenes. Further additions extend produce, successively, Cl5 farnesyl (FDP), sesquiterpenes, triterpenes sterols, C20 geranylgeranyl (GGDP), rise diterpenes phytol, provides sidechain chlorophylls and, most cases, bacteriochlorophylls. general outline pathway, illustrating relation compounds, given Fig. 4.1