نتایج جستجو برای: diphosphates
تعداد نتایج: 2906 فیلتر نتایج به سال:
A modified purification is described for an enzyme, from Escherichiacoli B, which polymerizes deoxyribonucleoside-5' diphosphates. Under appropriate conditions, the enzyme will add a single deoxyribonucleotide residue to a deoxyribo-oligonucleotide primer. At all stages, the enzyme activity copurified with the activity which will polymerize adenosine-5' diphosphate (polynucleotide phosphorylase...
Ribonucleotide reductase (RNR) catalyzes the conversion of nucleoside diphosphates to deoxynucleoside diphosphates. Crucial for rapidly dividing cells, RNR is a target for cancer therapy. In eukaryotes, RNR comprises a heterooligomer of alpha(2) and beta(2) subunits. Rnr1, the alpha subunit, contains regulatory and catalytic sites; Rnr2, the beta subunit (in yeast, a heterodimer of Rnr2 and Rnr...
BACKGROUND Ribonucleotide reductase catalyzes the conversion of ribonucleotide diphosphates to deoxyribonucleotide diphosphates. The functional enzyme consists of two subunits - one large (RRM1) and one small (RRM2 or RRM2b) subunit. Expression levels of each subunit have been implicated in prognostic outcomes in several different types of cancers. EXPERIMENTAL DESIGN Immunohistochemistry for...
Nucleoside triphosphates were examined as the activator for various nucleoside diphosphate reductions catalyzed by a highly purified ribonucleotide reductase obtained from Molt-4F cultured human cells. It was found that cytidine 5'-diphosphate and uridine diphosphate reductions are activated by adenosine 5'-triphosphate with apparent Ka's of 0.63 +/- 0.03 (S.E.) and 1.25 +/- 0.10 mM, respective...
The biosynthetic pathways to isoprenoid compounds involve transfer of the prenyl moiety in allylic diphosphates to electron-rich (nucleophilic) acceptors. The acceptors can be many types of nucleophiles, while the allylic diphosphates only differ in the number of isoprene units and stereochemistry of the double bonds in the hydrocarbon moieties. Because of the wide range of nucleophilicities of...
Polyisoprenoids or polyprenyls are lipids formed by the sequential condensation of the Ci unit of isopentenyl (3-methylbut-3-enyl) diphosphate with its allylic isomeric form, 3,3-dimethylallyl diphosphate and with further allylic diphosphates resulting from such condensation. The polyprenyl diphosphates function as donors or intermediates in the synthesis of numerous products which include ster...
Functional gene clusters, containing two or more genes encoding different enzymes for the same pathway, are sometimes observed in plant genomes, most often when the genes specify the synthesis of specialized defensive metabolites. Here, we show that a cluster of genes in tomato (Solanum lycopersicum; Solanaceae) contains genes for terpene synthases (TPSs) that specify the synthesis of monoterpe...
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