5 -Monophosphate uridine

Shaw synthesis, 3, 109 Uridine, 2 -deoxy-5-iodo-as pharmaeeutical, 1, 160 Uridine 5 -monophosphate biosynthesis, 1, 88 Uridylic acids occurrence, 3, 142 Urispas... 

A. The pyrimidine ring is synthesized first and is then attached to ribose 5- ph os-phate to eventually produce the nucleotide uridine 5 -monophosphate (UMP). 

Candida utilis is grown to high biomass concentrations and the extracted RNA is subsequently hydrolysed into the four 5 nucleotides adenosine 5 -monophosphate (AMP), GMP, cytidine and uridine 5 -monophosphate by crude nuclease PI from Penicillium the desired nucleotides are isolated by ion-exchange chromatography and AMP is converted to IMP by adenyl deaminase from Aspergillus [22, 36]. 

The common pyrimidine ribonucleotides are cytidine 5 -monophosphate (CMP cytidylate) and uridine 5 -monophosphate (UMP uridylate), which contain the pyrimidines cytosine and uracil. De novo pyrimidine nucleotide biosynthesis (Fig. 22-36) proceeds in a somewhat different manner from purine nucleotide synthesis the six-membered pyrimidine ring is made first and then attached to ribose 5-phosphate. Required in this process is carbamoyl phosphate, also an intermediate in the urea cycle (see Fig. 18-10). However, as we noted... 

The last two steps in the biosynthesis of the mononu- cl cotide uridine 5 -monophosphate (UMP) are catalyzed by (1) orotate phosphoribosyltransferase (OPRTase) and (2) orotate 5 -monophosphate decarboxylase (OMPDase). 

Nucleotides are nucleosides that have been phosphorylated on the 5 -hydroxyl group. One, two, or three phosphates can be added. Nucleotides are generally named by appending monophosphate, diphosphate, or triphosphate to the end of the name of the corresponding nucleoside, and the names are typically abbreviated. The suffixes -MP, -DP, and -TP correspond to mono-, di-, and triphosphate, respectively. Examples of 2 -deoxyadenosine 5 -diphosphate or ADP (6.13) and uridine 5 -monophosphate or UMP (6.14) are shown in Figure 6.5. 

Urea is another prebiotic condensing agent for the phosphorylation of nucleosides. Condensed phosphates have been obtained from ammonium phosphate and urea [126], while alcohols are easily phosphorylated at 150 °C by urea and phosphoric acid [127]. When an equimolar mixture of uridine 48 and Na2HP04 was heated at 100 °C in the presence of a ten-fold molar excess of urea and ammonium chloride, 97% of the phosphate was found to be incorporated into the nucleoside moiety mainly as uridine 5 -monophosphate 49 and uridine 2, 3 - cyclic phosphate 50 (Scheme 23). 

The thermal decarboxylation of 1,3-dimethylorotic acid 56 was studied as a model for uncatalysed decarboxylation of orotidine 5 -monophosphate to form uridine 5 -monophosphate.97 This reaction catalysed by the enzyme oritidine 5 -monophosphate decarboxylase is the essential step in nucleic acid biosynthesis.98 Samples of 1,3-dimethylorotic acid were heated at 190°C to conversion over 90% and unreacted substrate was recovered after conversion into the methyl ester. 

UDP-glucose, uridine 5 -diphosphate a-D-glucopyranosyl ester UMP, uridine 5 -monophosphate UTP, uridine 5 -triphosphate... 

Pyrimidine-5 -nucleotidase effects the release of phosphate from cytidine-5 -monophosphate and uridine-5 -monophosphate and thus is an enzyme involved in the catabolism of RNA. RNA is a normal constituent of reticulocytes but not of mature RBCs. In the absence (or notable deficiency) of P-5 -N, RNA persists in RBCs and is manifested by striking basophilic stippling and mild to moderate hemolytic anemia. 

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