Enhancer Cytidine

Ford, S. R., Hall, M. S., and Leach, F. R. (1992). Enhancement of firefly luciferase activity by cytidine nucleotides. Anal. Biochem. 204 283-291. 

Raynal, N.J., Bernstein, M.L. and Momparler, R.L. (2009) Inhibition of cytidine deaminase by zebularine enhances the antineoplastic action of5-aza-2 -deoxycytidine. Cancer Chemotherapy and Pharmacology, 63, 411-416. 

Thymidine phosphate and cytidine phosphate do not phosphoresce in a rigid ethylene glycol-water glass at 77°K109 when directly excited, but thymidine which has lost its proton at Nx does have a triplet which phosphoresces with a decay time of 0.50 sec at high pH uridine also fluoresces with a similar decay time. The quenching of purine fluorescence and appearance of T" fluorescence in UV-irradiated DNA and poly dAT (as well as U" fluorescence in poly rAU) was attributed by Rahn et al.109 to proton transfer from thymine to adenine. This quenches adenine fluorescence and enhances thymine fluorescence. 

Cytidine reacts in the same way, but the bisulfite addition compound is unstable. These C5-C6 adducts of cytidine all have a greatly enhanced reactivity at C4,... 

Brunner, C., Seiderer, J., Schlamp, A, Bidlingmaier, M., Eigler, A, Haimerl, W. et al. (2000) Enhanced dendritic cell maturation by TNF-alpha or cytidine-phosphate-guanosine DNA drives T cell activation in vitro and therapeutic anti-tumor immune responses in vivo. J. Immunol., 165, 6278-6286. 

Figure 2.5 Logarithmic scale comparison of k,d and kuncat (= (rnon) for some representative reactions at 25 °C. The length of each vertical bar represents the rate enhancement. (Wolfenden, 2001). ADC arginine decarboxylase ODC orotidine 5 -phosphate decarboxylase STN staphylococcal nuclease GLU sweet potato /3-amylase FUM fumarase MAN mandelate racemase PEP carboxypeptodase B CDA E. coli cytidine deaminase KSI ketosteroid isomerase CMU chorismate mutase CAN carbonic anhydrase.

Here, A stands for adenosine, T for thymine, G for guanosine, and C for cytidine) Because of its sixth-power dependence on interproton distances, the NOE is a very sensitive means of exploring molecular contacts through interproton distances. For large molecules such as these, the enhancement is negative. In Figure 8 are shown difference spectra for the aromatic protons of the netropsin complex with this nucleotide,... 

Ldpez G.-Coviella, I. and Wurtman, R.J. (1992) Enhancement by cytidine of membrane phospholipid synthesis. J. Neuro-chem. 59 338-343. 

Ramiro, A. R., Stavropoulos, P., Jankovic, M., and Nussenzweig, M. C. (2003). Transcription enhances AID-mediated cytidine deamination by exposing single-stranded DNA on the nontemplate strand. Nat. Immunol. 4, 452-456. 

PRODUCTS OF NUCLEIC ACID METABOLISM Nucleotides are excreted by yeast early in fermentation [91] and also under certain conditions of storage [91, 92]. Yeast is not the sole source of these compounds, malt being a particularly rich source. Free bases are reported to modify beer flavour, thus xanthine, guanine and cytidine enhance bitterness whereas adenine slightly depresses flavour [93]. 

The Hoogsteen hydrogen bonding motif between cytidine and adenine (shown below) requires that the cytidine be protonated, and in fact as the pH is lowered below 7 to between 5 and 6, triple helical DNA formation is enhanced. 

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