Uridine 5-pyrophosphate

A uridine pyrophosphate derivative of Ai -acetyl-n-glucosamine which contains an extra phosphate group has been isolated from a hot-water extract of hen oviducts. Uridine 5-phosphate and uridine 5-pyrophosphate have been recovered from acid hydrolyzates of this compound. A diphosphate ester of A-acetyl-n-glucosamine can also be obtained from acid hydrolyzates of this uridine compound. Because of the catalytic activity of phospho-A -acetyl-n-glucosamine mutase toward it, it is probably AT-ace-tyl-D-glucosamine 1,6-diphosphate. 

Rat-liver nuclei also catalyze the formation of a uridine pyrophosphate derivative of n-glucosamine from a-n-glucosamine 1-phosphate and uridine-5-triphosphoric acid. ... 

Particulate preparations of Staphylococcus aureus (Copenhagen) catalyze the transfer of 2-acetamido-2-deoxy-D-glucosyl residues from the uridine pyrophosphate derivative to teichoic acid from which n-alanine residues and 2-acetamido-2-deoxy-D-glucosyl residues have been removed. Intact teichoic acid is inert as a precursor. The ratio of a-n- to /3-n-linkages in the product synthesized by an unfractionated enzyme was 85 to 15. 

Uridine 5 -(trihydrogen diphosphate) mono-a-D-xylopyranosyl ester, 9 CL Uridine 5 -diphosphoxylose. Uridine pyrophosphate xylose ester [3616-06-6]... 

The Biosynthesis of the Pyrimidine Ring begins with aspartic acid and carbamyl phosphate. The latter is an energy-rich compound which reacts with the former to give carbamylaspartic acid. Ring closure consumes ATP and is in principle an acid amide formation (peptide synthesis). The intermediate dihydro-orotic acid is dehydrogenated to orotic acid, probably by action of a flavoprotein. Orotic acid is the key precursor of pyrimidine nucleotides. It reacts with phosphoribosyl pyrophosphate. The removal of pyrophosphate yields the nucleotide of orotic acid, whose enzymic decarboxylation produces uridine 5 -phosphate. Phosphorylation with ATP yields uridine pyrophosphate and, finally, uridine triphosphate. Beside the above pathway, there is the further possibility of converting free uracil and ribose 1-phosphate to the nucleoside and from there with ATP to the nucleotide. 

Kenner, G.W., Todd, A.R., Weymouth, F.J. (1952) Nucleotides. Part XVII. N-Chloroamides as Reagents for the Chlorination of Diesters of Phosphorous Acid. A New Synthesis of Uridine-5 Pyrophosphate. Journal of the Chemical Society, 3675-3681. 

Park, J. T. Uridine-5 -pyrophosphate Derivatives. II. J. biol. Chemistry... 

Handschuh and Orgel (1973) studied the mineral struvite. It can be precipitated from ocean water in the presence of phosphate if the concentration of NH ions in the water is greater than 0.01 M. If struvite is heated with urea, magnesium pyrophosphate is obtained in a yield of about 20% after 10 days at 338 K if nucleosides are added to the reaction mixture described above, nucleoside diphosphates such as uridine-5 -diphosphate and diuridine-5 -diphosphate are formed in good yields. 

Figure 20.9 The positions in the pathway for de novo pyrimidine nucleotide synthesis where GLUCOSE provides the ribose molecule and GLUTAMINE provides nitrogen atoms. Glucose forms ribose 5-phosphate, via the pentose phosphate pathway (see chapter 6), which enters the pathway, after phosphorylation, as 5-phospho-ribosyl 1-pyrophosphate. Glutamine provides the nitrogen atom to synthesise carbamoylphos-phate (with formation of glutamate), and also to form cytidine triphosphate (CTP) from uridine triphosphate (UTP), catalysed by the enzyme CTP synthetase. It is the amide nitrogen of glutamine that is the nitrogen atom that is provided in these reactions.

The purine and pyrimidine bases can be converted to then-respective nncleotides by reaction with 5-phosphoribosyl 1-pyrophosphate. Since these bases are not very soluble, they are not transported in the blood, so that the reactions are only of qnantitative significance in the intestine, where the bases are produced by degradation of nucleotides. In contrast, in some cells, nucleosides are converted back to nucleotides by the activity of kinase enzymes. In particular, adenosine is converted to AMP, by the action of adenosine kinase, and uridine is converted to UMP by a uridine kinase... 

Two steps aspartate PRPP, 5 -phosphoribosyl-1 -pyrophosphate UMP, uridine... 

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