The effects of γ-irradiation on the hydration characteristics of DNA and polynucleotides. III. A comparative NMR study of frozen and liquid solutions

The effects of γ-irradiation and changes in the macromolecular structure on the water proton resonance spectra observed in frozen and liquid solutions have been compared for the DNA and polynucleotide solutions, using H2O or mixed H2O/D2O solvents. The results indicate that in order to obtain information concerning the role of hydration water in mediating the overall radiation damage, the NMR studies must be performed in the frozen state.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

An NMR study of the relative interaction abilities of different pyrimidine nucleosides with serotonin

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

The effects of γ irradiation on the hydration characteristics of DNA and polynucleotides. II. An NMR study of mixed H2O/D2O frozen solutions

We have studied the effects of γ irradiation at different temperatures on the hydration water proton resonance spectra from frozen H2O/D2O solutions of DNA and polynucleotides. Comparison of results obtained with pure H2O solutions showed a striking difference in the temperature-dependent variations of Δ(1/2) values in nonirradiated and irradiated DNA solutions. There is evidence that base rehydration with hydration water molecules occurs after an initial damage to the macromolecular chains in DNA caused by the direct or indirect radiation effects.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

The effects of γ irradiation on the hydration characteristics of DNA and polynucleotides. I. An NMR study of frozen H2O and D2O solutions

Water proton and deuteron resonance spectra have been studied in frozen solutions of DNA, poly(A), poly(C), poly(U), poly(A+U) and poly (A+2U) at different temperatures between -5 and -40°C. Hydration water molecules exhibit high proton and molecular mobility in frozen solutions and are responsible for the observed spectra. The γ irradiation of solutions at O and -80°C results in striking changes in the proton spectra and no change in the deuteron spectra. These results suggest that proton exchange is an important factor in affecting the proton linewidth and the proton relaxation mechanism. The changes in molecular structure (either by γ irradiation or molecular association) influence the hydration water in a characteristic manner. The effects of irradiation at different temperatures (O, -80, and -196°C) suggest that hydration water makes a distinct contribution to the overall radical attack on the DNA molecule from the water medium.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Quality assessment in in vivo NMR spectroscopy. VI. Multicentre quantification of MRS test signals.

A numerical procedure is presented for mapping the vicinity of the null-space of the spin relaxation superoperator. The states populating this space, i.e. those with near-zero eigenvalues, of which the two-spin singlet is a well-studied example, are long-lived compared to the conventional T(1) and T(2) spin-relaxation times. The analysis of larger spin systems described herein reveals the presence of a significant number of other slowly relaxing states. A study of coupling topologies for n-spin systems (4≤n≤8) suggests the symmetry requirements for maximising the number of long-lived states