Nucleotide plant, biosynthesis

Major enzyme reactions involved in the transfer of Cl moieties and the concomitant transformations of the cognate coenzyme forms are summarized in Table 1. Whereas animals use folate-type coenzymes predominantly for the biosynthesis of nucleotides, plants and many microorganisms require them also for the biosynthesis of several essential amino acids. A detailed description of the metabolic pathways that depend on the cooperation of folate-type coenzymes is beyond the scope of the present chapter. 

Negishi, O., Ozzawa.T., and Imagawa, H., Biosynthesis of caffeine from purine nucleotides in tea plant, Bioscience, Biotechnology, and Biochemistry, 56,499,1992... 

The first nucleotide sequence for CHS was determined from cultured parsley cells [53]. Since then, its expression and regulation have been extensively studied in numerous plant systems in relation to a myriad of different conditions and stimuli [e.g., 21 and ref therein]. Due to its key role in flavonoid biosynthesis, CHS has been a popular target for various gene-silencing techniques in attempts to generate flavonoid-deficient plants [16, 54 and ref therein]. 

The biosynthetic pathway producing isoprenoid cytokinins has been identified, whereas that of aromatic cytokinins is poorly characterized.363 385 Two distinct pathways for isoprenoid cytokinin biosynthesis have been described, and each pathway employs a different type of isopentenyltransferase at the initial step. The major pathway in higher plants, which is catalyzed by IPT, is conjugation of adenine nucleotide and DMAPP or 4-hydroxy-3-methyl-2-( )-butenyl diphosphate (HMBDP) (Figure 14). In the less frequently used pathway, cytokinins are formed by degradation of prenylated tRNAs. The initial prenylation reaction of tRNA is catalyzed by tRNA-isopentenyltransferase (tRNA-IPT) (Figure 14). 

In the form of deoxyribonucleic acid (DNA), the macromolecular nucleic acids are of prime importance in biology because they carry the building plan for each living individual. They are identically reduplicated and inherited from one generation to the next, be it bacterium, plant, animal, or man. The information about every feature of and about every molecule contained in a living being is encoded in the nucleotide sequence of its DNA, which is read out and translated into the amino acid sequences of its proteins. In the many different steps involved in this protein biosynthesis, information transfer takes place which would be impossible without the weak hydrogen bonds. Because they can easily and rapidly be formed and broken, they are ideally suited for these dynamic processes which are so important for life. 

Tenhaken, R., and Thulke, O., 1996, Cloning of an enzyme that synthesizes a key nucleotide-sugar precursor of hemicellulose biosynthesis from soybean UDP-glucose dehydrogenase. Plant Physiol. 112 1127-1134. 

Seifert GJ. Nucleotide sugar interconversions and cell wall biosynthesis how to bring the inside to the outside. Curr. Opin. Plant Biol. 2004 7 277-284. 

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