Biosynthesis of carotene

Goodwin T and Jamikorn M. 1952. Biosynthesis of carotenes in ripening tomatoes. Nature 170 104—105. 

Hamauzu Y and Chachin K. 1995. Effect of high-temperature on the postharvest biosynthesis of carotenes and alpha-tocopherol in tomato fruit. J Jap Soc Hort Sci 63 879—886. 

Bleaching herbicides is another type that is heavily represented by heterocyclic compounds. Norflurazon and fluridone are examples of these heterocyclic herbicides, these compounds exhibit their action by interrupting the biosynthesis of carotene in the plant. This leads to the destruction of the chlorophyll in the plants, which turn a characteristic white or pink color. 

The bright red pigment found in tomatoes (also in carrots, watermelons, papaya) is lycopene (3.17). It is key intermediate in the biosynthesis of carotenes (using an enzyme called lycopene cyclase), but lycopene from the diet cannot be converted to vitamin A. Both carotene and lycopene are known to be antioxidants and are supposed to retard the aging process. 

PORTER J w and Lincoln r e (1950) Lycopersicon selections containing a high content of carotenes and colourless polyenes II. The mechanism of carotene biosynthesis , yfrc/iiv Biochem Biophys, 27, 390-95. 

Replacement of the hydrogen at the 3 or 3 position of the carotene ring with a hydroxyl is the next step in both branches of the pathway. Hydroxylation of the rings of the carotenes leads to biosynthesis of the xanthophylls, including the well-known lutein and zeaxanthin food pigments. Lutein is formed by hydroxylation of a-carotene zeaxanthin is formed by hydroxylation of P-carotene. 

Cunningham, F.X. Jr. et ah. Cloning and functional expression in Escherichia coli of a cyanobacterial gene for lycopene cyclase, the enzyme that catalyzes the biosynthesis of beta-carotene, FEBS Lett. 328, 130, 1993. 

Breitenbach, J., Vioque, A., and Sandmann, G., Gene sll0033 from Synechocystis 6803 encodes a carotene isomerase involved in the biosynthesis of aU-E lycopene,... 

Juttner, F. (1979). Algal excretion product, geranylacetone-potent inhibitor of carotene biosynthesis in syn-echococcus. Zeitschrift Naturforschung C 34(11) 957-960. 

Wang, X. D., N. I. Krinsky, P. N. Benotti, and R. M. Russell. 1994. Biosynthesis of 9-cis-retinoic acid from 9-cis-beta-carotene in human intestinal mucosa in vitro. Arch Biochem Biophys 313(1) 150-155. 

Inhibitors have been used to investigate the biosynthesis of 1,2-dihydroneuro-sporene [l,2,7,8-tetrahydro-i/, i/f-carotene (143)] and related 1,2-dihydro-carotenoids in Rhodopseudomonas viridis, and possible alternative sequences are presented.The C-1,2 hydrogenation reaction is inhibited by CPTA [2-(4-chlorophenylthio)triethylammonium chloride], a compound known to inhibit cyclization and C-1,2-hydration in other systems, thus indicating possible similarity of the reactions involved. 

Pathways for the biosynthesis of the cyclopentane carotenoids capsanthin [3,3 -dihydroxy- 8,K-caroten-6 -one (146)] and capsorubin [3,3 -dihydroxy-ir,K-caro-tene-6,6 -dione (147)] have been proposed from consideration of the carotenoids identified in extracts of lilies and red peppers. 

Isoprene is also a precursor of steroids and terpenes. This relationship becomes clear when we examine the biosynthesis of these compounds (see chapter 20). Vitamin A is either biosynthesized from /3-carotene (see fig. S2.4) or absorbed in the diet. Vitamin A is stored in the liver predominantly as an ester of palmitic acid. For many decades, it has been... 

Figure 6.6 Biosynthesis of various vitamin A derivatives from /3-carotene and their role in human physiology.

Besides the engineering of S. cerevisiae for organic acid production, through metabolic engineering it is possible to reconstruct entire pathways. In 1994, Yamano et al. [163] reported the reconstruction of a complete secondary metabolic pathway in S. cerevisiae, resulting in the ability of the yeast to produce p-carotene and lycopene. Carotenoids are a class of pigments used in the food industry and, due to their antioxidant properties, they have wide commercial interest. The biosynthesis of these compounds does naturally not occur in S. cerevisiae and to allow... 

Figure 11 Biosynthesis of isoprenoid type cofactors. 18, Heme a 39, pyridoxal 5 -phosphate 43, 1-deoxy-D-xylulose 5-phosphate 46, thiamine pyrophosphate 83, acetyl-CoA 84, (S)-3-hydroxy-3-methylglutaryl-CoA 85, mevalonate 86, isopentenyl diphosphate (IPP) 87, dimethylallyl diphosphate (DMAPP) 88, pyruvate 89, D-glyceraldehyde 3-phosphate 90, 2C-methyl-D-erythritol 4-phosphate 91, 2C-methyl-erythritol 2,4-cyclodiphosphate 92, 1-hydroxy-2-methyl-2-( )-butenyl 4-diphosphate 93, polyprenyl diphosphate 94, cholecalciferol 95, fS-carotene 96, retinol 97, ubiquinone 98, menaquinone 99, a-tocopherol.

The first chapter in the herbicide section is devoted to synthetic efforts related to the herbicide Command, currently being developed by FMC Corporation. Here we see detailed the various synthetic and structure-activity relationships of this important group of compounds. These compounds exert their phytotoxic effect by their bleaching action on a wide variety of economic weeds. An important observation was that soybeans were not affected at normal use rates. These compounds act upon the carotene and chlorophyll biosynthesis of the plant. Here are a group of synthetic pathways that are peculiar to plants and a few microorganisms and are susceptible to chemical attack. 

Low O2 generally delays or Inhibits the synthesis of lycopene, 11-carotene, and xanthophylls In tomato fruit (31.321. In sweet pepper, high COg delayed development of red color equally whether combined with 21% or 3% 02 (33). C2H4 Is known to accelerate the biosynthesis of carotenoids (34). 

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