Nucleotides Cytosine

Fosfadecin (186) and fosfocytocin (187) are adenine and cytosine nucleotide antibiotics isolated from the culture filtrates of Pseudomonas viridiflava PK-5 and P. fluorescens PK-52, respectively (283). Hydrolysis produces fosfoxacin which is also isolated from the culture filtrates. Compounds (186) and (187) inhibit gram-positive and gram-negative bacteria. 

The terms first, second, and third nucleotide refer to the individual nucleotides of a triplet codon. U, uridine nucleotide C, cytosine nucleotide A, adenine nucleotide G, guanine nucleotide Term, chain terminator codon. AUG, which codes for Met, serves as the initiator codon in mammalian cells and encodes for internal methionines in a protein. (Abbreviations of amino acids are explained in Chapter 3.)... 

The carbon monoxide dehydrogenase of the aerobe Oligotropha carboxidovorans contains both Cu and Mo in the form of a cluster in which the Mo is bound to the thiol groups of molybdopterin cytosine nucleotide, and the Cu to cysteine residue in the form of a Cu-S-Mo(=0)OFl cluster (Dobbek et al. 2002). 

Briozzo, P. Golinelli-Pimpaneau, B. Gilles, A.M. Gaucher, J.R Burlacu-Miron, S. Sakamoto, H. Janin, J. Barzu, O. Structures of Escherichia coli CMP kinase alone and in complex with CDP a new fold of the nucleoside monophosphate binding domain and insights into cytosine nucleotide specificity. Structure, 6, 1517-1527 (1998)... 

Fosfadecin and fosfocytocin are adenine and cytosine nucleotide antibiotics isolated from culture filtrates of Pseudomonas species. Fosfadecin and fosfocytocin inhibit gram-positive and gram-negative bacteria. 

Cidofovir is a cytosine nucleotide analog with in vitro activity against CMV, HSV-1, HSV-2, VZV, EBV, HHV-6, HHV-8, adenovirus, poxviruses, polyomaviruses, and human papillomavirus. In contrast to ganciclovir, phosphorylation of cidofovir to the active diphosphate is independent of viral enzymes. After phosphorylation, cidofovir acts both as a potent inhibitor of and as an alternative substrate for viral DNA polymerase, competitively inhibiting DNA synthesis and becoming incorporated into the viral DNA chain. Isolates with resistance to cidofovir have been selected in vitro these isolates tend to be cross-resistant with ganciclovir but retain susceptibility to foscamet. Clinically significant resistance to cidofovir has not been reported to date. 

The infected system was shown to contain deoxymidine 5-phosphate this observation is interesting, since this nucleotide has not yet been shown to be present in normal cells. The nucleotide is presumably used for the synthesis of thymidine 5-triphosphoric acid. Detectable quantities of 5-(hydroxymethyl)cytosine or of 5-(hydroxymethyl)cytosine nucleotides were not present, despite the fact that this base is a normal constituent of the phage deoxyribonucleic acid. Explanations for this observation are that (a) the amount present in the acid-soluble fraction at any given moment is too small for detection by the methods of anal3rsis employed, or (b) the newly synthesized 5-(hydroxymethyl)cytosine is directly incorporated into deoxyribonucleic acid. 

The phosphoglycerides may be synthesized from compounds containing cytosine nucleotides, or they may be interconverted (e.g., phosphatidyl-... 

D. CDP-choline reacts with a diacylglycerol to form phosphatidylcholine. UDP-galactose reacts with ceramide to form a galactocerebroside. Cytosine nucleotides are not required for... 

Cidofovir (5) is a cytosine nucleotide analog which is active in vitro against CMV, HSV-1, -2, VZV, EBV, adenovirus and human papillomavirus. Phosphorylation of 5 is independent of viral infection [13]. 

If possible, within the last five nucleotides of the 3 end, there should be no more than two guanosine and/or cytosine nucleotides. 

Table 5 contains ribonucleotides with the common amino and carbonyl structures, with extra substituents, and with totally unsubstituted bases like purine or benzimidazole. Apparent values and velocities do not vary more than about tenfold in the presence of specific effector deoxyribonucleotides. Guanine and cytosine nucleotides have usually fastest and compounds with fewer base substituents show decreased reaction rates. Loss of substrate activity is only observed in syn-oriented nucleotides where the nucleobase is rotated about the glycosidic bond like in 8-bromo-ADP or -ATP. Molecular conformation-enzyme activity relationships have been discussed in detail ... 

D17 Domschke, W., Keppler, D., Bischoff, E. and Decker, K. Cytosine nucleotides in liver. Hoppe-Seyler s Z. Physiol. Chem., 352, 275-279 (1971)... 

Fig. 4.3 Comparative strueture of natural (cyclic) and acyclic cytosine nucleotides a natural nucleotide 2 -deoxycytidine-5 -monophospate, b acyclic nucleotide cidofovir...

Ion-exchange separation of such digests shows the presence of four major components corresponding to the adenine, guanine, thymine, and cytosine nucleotides." They are believed to be the four nucleoside 5 -phosphates for the following reasons Desoxyadenylic acid behaves identically with adenosine-5 -phosphate on the ion-exchange column. Desoxycytidylic acid and synthetic cytidine-5 -phosphate likewise behave in an identical fashion. All four desoxynucleotides are split by 5-nucleotidase purified from bull semen, which is specific for nucleotides containing phosphate esterified at carbon 5 (see below). Finally, desoxyadenylic acid yields ammonia on incubation with Schmidt s deaminase, which also acts on adenosine-5 -phosphate but not adenosine-3 -phosphate. 

If a sample of DNA isolated from a microorganism culture were analyzed and found to contain 1.5 mol of cytosine nucleotides and 0.5 mol of adenosine nucleotides, what would be the amounts of guanine and thymine nucleotides in the sample ... 

The work of Nyc and associates on the lipids of Neurospora crassa is of particular interest in relation to the bios3mthesis of lecithin. The phospholipid of a choline-requiriug mutant contains the phosphatidyl esters of both mono- and di-methylaminoethanol (Hall and Nyc 1961). Nutritional studies with appropriate mutants of this organism have shown that lecithin may be formed (a) from choline by the cytosine nucleotide pathway (Reactions 11 and 12), (b) from phosphatidyl ethanolamine by the methylation pathway (Reactions 13,14 and 15) and (c) from mono- and di-methylaminoethanol by the incorporation of the base into lipid, presumably by way of CDP-intermediates, followed by methylation. The relative contributions of these pathways can be influenced by mutations and by nutritional supplementation of the culture medium (Crocken and Nyc 1964). 

The finding of McMurray et al. (1957) that the addition of CTP increases the incorporation of inorganic P into the phosphatidyl inositol of brain preparations imphcated a cytosine nucleotide in the biosynthesis of this lipid. It is now believed that phosphatidyl inositol is formed by a phosphatidyltransferase reaction in which a phosphatidyl group is transferred to free myoinositol from CDP-diglyceride ... 

Metabolism of phosphatides in developing rat brain. — II. Labelling of plasmalogens and other alkali-stable lipids from radioactive cytosine nucleotides. J. Neurochem. 11,315— 26 (1964b). 

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