Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Thymidine shift

The crystal and molecular structure of the 44, 45, and C5-vinylferro-cenyl-thymidine show that the substituted cyclopentadienyl ring is essentially co-planar with the nucleobase (164). DFT calculations indicate that, irrespective of the extent of saturation in the bridging C2-unit in ethynyl-, vinyl- or ethyl-ferrocenyl-C5-thymidine, a similar amount of spin density is transferred to the nucleobase (Fig. 48). The reduction potentials for these compounds are shifted little compared to the parent ferrocenyl derivatives. [Pg.138]

Cifone, M.A., Myhr, B., Eiche, A. and Bolisfodi, G. (1987). Effect of pH shifts on the mutant frequency at the thymidine kinase locus in mouse lymphoma L5178Y TK+/— cells. Mutation Res. 189 39-46. [Pg.228]

The similarity in the pyrimidine carbon resonances in cytidine and deoxycytidine is indicative of the independence of these shifts from the sugar fragments. The differences observed between the chemical shifts of uracil and thymine, or uridine and thymidine, indicate that they must result from the presence of the 5-methyl group in the latter. The downfield shifts ( — 7.5 ppm) of the 05 peaks of uracil or uridine upon 5-methyl substitution are typical for a carbon directly substituted by a... [Pg.332]

Fig. 5.10. Plot of 13C chemical shifts versus rc-charge densities [749], calculated by Fcrnan-dez-Alonso [765]. (Adenosine O, guanosine n, inosine A, xanthosine O, uridine . cyti-dine , thymidine .)... Fig. 5.10. Plot of 13C chemical shifts versus rc-charge densities [749], calculated by Fcrnan-dez-Alonso [765]. (Adenosine O, guanosine n, inosine A, xanthosine O, uridine . cyti-dine , thymidine .)...
The configurations of the cyclic thymidine 3, 5 -[170, 180]-monophosphates can be conveniently assigned by 170 NMR spectroscopy. We have previously reported that in aqueous solution at 95° C the 170 NMR chemical shifts of the phosphoryl oxygens of cyclic 2 -deoxyadenosine 3, 5 -[170, 180]monophosphate are sufficiently different at 36.6 MHz such that two resonances can be resolved in a racemic mixture of the diastereomers, with the down-... [Pg.110]

H2O solution (6 to 14 ppm) were recorded between 0° and 55°C and the exchangeable protons identified by comparison with the corresponding spectra recorded in 20 solution. The thymidine H-3 imino hydrogen-bonded resonance is observed at 13.0 ppm in the spectrum of poly(dA-dT) at 25.5°C (Figure 1A) and its chemical shift and line width dependence are plotted as a function of temperature in Figures IB and 1C respectively. [Pg.220]

NMR spectrum of the thymidine H-3 proton in polv(dA-dT) in 0.1 M phosphate, ImM EDTA, H,0 at 25.5°C. The (B) chemical shifts and (C) iinewidths of this proton in the synthetic DNA in 0.1 M phosphate are plotted as a function of temperature between 0° and 55°C. The poly(dA-dT) duplex exhibits a duplex-to-strand transition midpoint of 59°C. [Pg.221]

The adenosine and thymidine base protons shift upfield to different extents on poly(dA-dT) duplex formation (Table I,... [Pg.226]

The chemical shifts are similar at high temperature and differ by uO.l ppm at the lower temperature (Figure 12). This suggests that similar base pair overlaps are observed for poly(dA-dT) in 1 M Na+ and 1 M TMA+ as monitored at the thymidine H-3 proton located in the center of the base pair. [Pg.237]

Figure 12. A comparison of the tern- g perature dependence of the thymidine H-3 proton chemical shift of poly(dA-dT) in 1M NaCl, lOmM cacodylate, O.lmM EDTA, H.O, pH 6.53 (9) and in /M (2H, C),NCl, lOmM phosphate, ImM EDTA, HiO, pH 7.5(0)... Figure 12. A comparison of the tern- g perature dependence of the thymidine H-3 proton chemical shift of poly(dA-dT) in 1M NaCl, lOmM cacodylate, O.lmM EDTA, H.O, pH 6.53 (9) and in /M (2H, C),NCl, lOmM phosphate, ImM EDTA, HiO, pH 7.5(0)...
The dissociation of the proflavine poly(dA-dT) complex can be followed by monitoring the temperature dependent chemical shift or the line width as demonstrated by shift data on the thymidine CH3-5 resonance (Figure 18A) and width data on the adenosine H-8 resonance (Figure 18B). The proton resonances shift as average peaks during the dissociation of the complex, indicative of fast exchange ( dissociation 10 sec l at the transition midpoint) between the complex and its dissociated components on the NMR time scale. [Pg.242]

Nucleic Acid Base Resonances The chemical shifts of the nonexchangeable protons in poly(dA-dT), the Nuc/D = 24 complex and the Nuc/D = 8 complex in 1 M NaCl solution are plotted as a function of temperature in Figure 19. The nucleic acid nonexchangeable proton chemical shifts in the duplex state are either unperturbed (adenosine H-8, H-2, and thymidine CH3-5) or shift slightly upfield (thymidine H-6) on complex formation (Figure 19). By contrast, the thymidine H-3 exchangeable proton located in the center of the duplex resonates 0.35 ppm to higher field in the Nuc/D = 8 proflavine complex compared to its position in the... [Pg.242]

Figure 18. The temperature dependence of (A) the thymidine CH.,-5 chemical shift and (B) the adenosine H-8 linewidth in poly(dA-dT) (O), the proflavine polv(dA-dT) complex, Nuc/D 24 (A) and Nuc/D = 8(9) in 1M NaCl, lOmM cacodylate, lOmM EDTA, sH.O, pH 7... Figure 18. The temperature dependence of (A) the thymidine CH.,-5 chemical shift and (B) the adenosine H-8 linewidth in poly(dA-dT) (O), the proflavine polv(dA-dT) complex, Nuc/D 24 (A) and Nuc/D = 8(9) in 1M NaCl, lOmM cacodylate, lOmM EDTA, sH.O, pH 7...
Chemical Shift of the Thymidine H-3 Proton In Poly(dA-dT) and Its Daunomycin Complex rnlMNaCl Solution... [Pg.259]

Base Proton Complexation Shifts The complexation shifts of certain nucleic acid base resonances of poly(dA-dT) on formation of the daunomycin neighbor exclusion complex reflect the shielding contribution due to the anthracycline ring less the contribution from one neighboring base pair which is displaced following intercalation. Thus, the adenosine H-2 resonance remains unperturbed (Figure 27) while the thymidine exchangeable H-3 proton... [Pg.260]

In the center of the duplex shifts upfield by 0.15 ppm (Table VI, Figure 25) and the thymidine CH3-5 which Is directed towards the major groove shifts upfield by 0.1 ppm (Figure 29). It should be noted that such an upfield shift of the thymidine CH3-5 group was not observed in the intercalation complexes of ethidium (11), proflavine (25), terpyridylplatinum II (11) and nitroaniline dication with poly(dA-dT). The results require that at least one thymidine CH3-5 group project onto the periphery of the anthra-cycline ring system at the intercalation site. [Pg.264]

Figure 37. The variation of the sugar H-l and base proton (adenosine II-8, H-2, and thymidine CH t-5) chemical shifts of 24mM poty(dA-dT) in 0.1 M cacodyiate, lOmM EDTA, 2HiO, pH 7.25, 53°C on gradual addition of netropsin... Figure 37. The variation of the sugar H-l and base proton (adenosine II-8, H-2, and thymidine CH t-5) chemical shifts of 24mM poty(dA-dT) in 0.1 M cacodyiate, lOmM EDTA, 2HiO, pH 7.25, 53°C on gradual addition of netropsin...
The observation of selective complexation shifts in the nucleic acid resonances of the synthetic DNA demonstrate a change in the glycosidic torsion angles of the adenosine and thymidine residues and a minimal perturbation in the base pair overlaps on addition of netropsin. These structural perturbations at the antibiotic binding site are propagated to adjacent antibiotic-free base pair regions at low netropsin concentrations. [Pg.287]


See other pages where Thymidine shift is mentioned: [Pg.85]    [Pg.248]    [Pg.277]    [Pg.877]    [Pg.331]    [Pg.113]    [Pg.113]    [Pg.220]    [Pg.222]    [Pg.222]    [Pg.231]    [Pg.231]    [Pg.237]    [Pg.257]    [Pg.272]    [Pg.272]    [Pg.273]    [Pg.277]    [Pg.281]    [Pg.289]    [Pg.104]    [Pg.331]    [Pg.172]    [Pg.461]    [Pg.54]    [Pg.223]    [Pg.183]    [Pg.130]   
See also in sourсe #XX -- [ Pg.259 ]




SEARCH



Thymidine

Thymidine chemical shift

© 2024 chempedia.info