Uracil triphosphate

In a separate study by Kovari etal., the authors report the use of CD spectroscopy to study the binding of Mg + to the DNA repair enzyme dUTPase. This enzyme catalyzes the hydrolysis of uracil triphosphate (UTP) to uracil monophosphate and inorganic pyrophosphate, leading to removal of excess uracil. The Mg + ion is an essential... 

ACS = anunonium (-l-)-DlO-camphorsulfonate BSA = bovine serum albumin CD = circular dichroism CT = charge transfer hCCS = human copper chaperone for superoxide dismutase hSCAN = human soluble calcium-activated nucleotidase-1 LMCT = ligand-to-metal charge transfer METP = miniaturized electron transfer protein MECT = metal-ligand charge transfer ORD = optical rotatory dispersion SODs = superoxide dismutases tCCS = tomato copper chaperone for superoxide dismutase UTP = uracil triphosphate. 

Fluoro-5 -methyl-beta-l-arabinofuranosyl uracil triphosphate (L-FMAU-TP)... 

Figure 12 Gradient separation of bases, nucleosides and nucleoside mono- and polyphosphates. Column 0.6 x 45 cm. Aminex A-14 (20 3 p) in the chloride form. Eluent 0.1 M 2-methyl-2-amino-l-propanol delivered in a gradient from pH 9.9-100 mM NaCl to pH 10.0-400 mM NaCl. Flow rate 100 ml/hr. Temperature 55°C. Detection UV at 254 nm. Abbreviations (Cyt) cytosine, (Cyd) cytidine, (Ado) adenosine, (Urd) uridine, (Thyd) thymidine, (Ura) uracil, (CMP) cytidine monophosphate, (Gua) guanine, (Guo) guanosine, (Xan) xanthine, (Hyp) hypoxanthine, (Ino) inosine, (Ade) adenosine, (UMP) uridine monophosphate, (CDP) cytidine diphosphate, (AMP) adenosine monophosphate, (GMP) guanosine monophosphate, (IMP) inosine monophosphate, (CTP) cytidine triphosphate, (ADP) adenosine diphosphate, (UDP) uridine monophosphate, (GDP) guanosine diphosphate, (UTP) uridine triphosphate, (ATP) adenosine triphosphate, (GTP), guanosine triphosphate. (Reproduced with permission of Elsevier Science from Floridi, A., Palmerini, C. A., and Fini, C., /. Chromatogr., 138, 203, 1977.)...

Uracil Uridine Uridylic acid Uridine monophosphate (UMP) Uridine diphosphate (UDP) Uridine triphosphate (UTP)... 

Deoxyrihonucleotides are generally formed by reduction of ribonucleoside diphosphates. This involves a series of redox reactions in which NADP+ and FAD play a role (see Section 15.1.1), with a subsequent electron transport chain. DNA contains thymine rather than uracil, so thymidine triphosphate (dTTP) is a requirement. Methylation of dUMP to dTMP is a major route to thymine nucleotides, and is dependent upon N, A °-methylenetetrahydrofolate as the source of the methyl group (see Box 11.13). 

Although FdUrd produces only DNA-medicated cyotoxicity, 5-FU can also be metabolized to fluorouracil monophosphate (FUMP) and ultimately to fluorouracil triphosphate (FUTP), which can be incorporated into RNA in place of uridine triphosphate (UTP). In other words, incorporation of 5-FU into RNA mimics uracil de novo synthesis and affects the production of ribosomal RNAs (rRNAs) (16,17). 5 -FU also affects several aspects of messenger RNA (mRNA) function, including transcription (18), translation (19), and slicing (20). 

There are three major types of RNA that participate in the process of protein synthesis ribosomal RNA (rRNA), transfer RNA (tRNA), and messenger RNA (mRNA). They are unbranched polymers of nucleotides, but differ from DNA by containing ribose instead of deoxyribose and uracil instead of thymine. rRNA is a component of the ribosomes. tRNA serves as an adaptor molecule that carries a spe dfic amino acid to the site of protein synthesis. mRNA carries genetic information from the nuclear DNA to the cytosol, where it is used as the template for protein synthesis. The process of RNA synthesis is called transcription, and its substrates are ribonucleoside triphosphates. The enzyme that synthesizes RNA is RNA polymerase, which is a multisub-irit enzyme. In prokaryotic cells, the core enzyme has four subunits—... 

The production of CTP by amination of UTP. The conversion of the pyrimidine ring of uracil to cytosine occurs at the level of the nucleotide triphosphate. The enzyme responsible for this conversion is known as cytidine triphosphate synthase. 

Since DNA contains thymine (5-methyluracil) as a major base instead of uracil, the synthesis of thymidine monophosphate (dTMP, or thymidylate) is essential to provide dTTP (thymidine triphosphate), which is needed for DNA replication together with dATP, dGTP, and dCTP. 

Despite these similarities, there are some very important differences between the reactions carried out by DNA polymerase and RNA polymerase. Remember that DNA is synthesized with the use of four deoxyn bon ucl cosidc triphosphates (dATP, dGTP, dTTP, and dCTP). In the double-stranded DNA helix, adenine bases hydrogen-bond with thymine bases, and guanine bases hydrogen-bond with cytosine bases. RNA, however, is synthesized with the use of four ribonucleoside triphosphates (ATP, GTP, CTP, and UTP). Adenine and guanine bases in the DNA template will direct the addition of uracil and cytosine bases to the growing RNA molecule, respectively, while... 

DNA strand 3 to 5 and produce a transcript in the 5 to 3 direction that is identical to the sequence of the coding DNA strand, with uracil (U) in place of thymine (T). A radiolabeled transcript can be produced by including an a-[52P] nucleotide, which will become part of the product, or by including a y-[52P] nucleoside triphosphate that is known to be the first nucleotide in the transcript. 

Kornberg s work on the biosynthesis of deoxyribonucleic acid has shown that enzymes in Escherichia coli extracts catalyze the formation of the 5-triphosphates of 2-deoxyadenosine, 2-deoxyguanosine, 2-deoxycyti-dine, and thymidine from the corresponding monophosphates in the presence of adenosine 5-triphosphate, but fail to catalyze phosphorylation of deoxyuridine 5-phosphate this finding could explain why uracil is not a constituent of deoxyribonucleic acid. 

Figure 2 The components of RNA. (a) The primary bases of RNA, which includes the purines adenine and guanine and the pyrimidines cytosine and uracil, (b) A purine nucleoside (adenosine) and a pyrimidine nucleoside (uridine), (c) The nucleotide adenosine 5 -triphosphate. (d) An RNA strand with the sequence AGCU.

How is the other major pyrimidine ribonucleotide, cytidine, formed It is synthesized from the uracil base of UMP, but UMP is converted into UTP before the synthesis can take place. Recall that the diphosphates and triphosphates are the active forms of nucleotides in biosynthesis and energy conversions. Nucleoside monophosphates are converted into nucleoside triphosphates in stages. First, nucleoside monophosphates are converted into diphosphates by specific nucleoside monophosphate kinases that utilize ATP as the phosphoryl-group donor (Section 9.4). For example, UMP is phosphorylated to UDP by UMP kinase. 

TPP thiamine pyrophosphate Trp tryptophan TTP thymidine triphosphate Tyr tyrosine U uracil... 

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