Proton NMR and spin lattice relaxation study of nucleoside di- and triphosphates in neutral aqueous solutions (original) (raw)
Related papers
Biochimica Et Biophysica Acta (bba) - Nucleic Acids and Protein Synthesis, 1974
The conformation of the three adenosine monophosphates in aqueous solution was studied by proton magnetic resonance and by the proton-proton Overhauser effect at 60 and 250 MHz. The results show that the ribose rings of adenosine monophosphates are not rigid but have similar conformations. The nuclear Overhauser effect suggests a predominant syn conformation for Ado-2'-P and Ado-3'-P and anti conformation for Ado-5'-P. The effect of concentration and temperature is small on the sugar conformation but it is important on the intermolecular association. The variations of the chemical shifts suggest that the stacking geometry is head-to-tail. The population of the three possible rotamers of the exocyclic CH2OH group has been evaluated and the results indicate that the gauche-gauche conformation is preponderant for the three Ado-P's.
Biochimica Et Biophysica Acta (bba) - Nucleic Acids and Protein Synthesis, 1972
The conformation oi the ribose of Guo-2'-P (guanosine 2'-phosphate) in aqueous solution was studied by proton magnetic resonance (PMR) at 60 and 25 ° MHz. The chemical shifts and the spin coupling constants JH-H' and JP-H2" are reported as a function of concentration, temperature and p2H. The results show that the conformations of Guo-2'-P are independent of concentration and temperature. The coupling constants JH-w suggest that the ribose is not rigid and that its mean conformation changes with the protonation of the base at N ~. There is no effect of protonation of the phosphate group on the sugar conformation. At low p2H values H 3, is statistically more axial than H,,, while the situation is inverse in neutral medium. This confirms previous results obtained by nuclear Overhauser effect on guanosine phosphates. The electronic environment of the exocyclic CH2OH group is independent of p2H. The population of the three possible rotamer forms of this group has been evaluated and the results indicate that the gauche-gauche conformation is preponderant.
Solid State Nuclear Magnetic Resonance, 2008
By combining magnetic field cycling in the range from 0.1 mT to 7 T with high-resolution NMR detection the T 1 relaxation dispersion (nuclear magnetic relaxation dispersion (NMRD)) of protons in the nucleotides adenosine mono-phosphate and guanosine mono-phosphate was measured in a sitespecific way. While at high field the individual spins have distinctly different T 1 times, their scalar spin-spin interaction fulfills at low field the condition of strong coupling and leads to convergence of their T 1 dispersion curves. In addition, the spin-spin coupling can lead to oscillatory components in the relaxation kinetics traceable to a coupling between spin polarization and coherence in the relaxation process. As a consequence the NMRD curves do not directly reflect the spectral density function of the motional processes, but the effects of motion and spin coupling must be separated for a reliable evaluation. A theoretical approach is described allowing such an analysis.
NMR Studies on the syn-anti Dynamic Equilibrium in Purine Nucleosides and Nucleotides
European Journal of Biochemistry, 1980
The s.yn + anti equilibrium conformation about the glycosidic bond of purine nucleosides and 5'-nucleotides in different solvent systems has been investigated by means of 'H NMR spectroscopy. Quantitative values for the conformer populations were improved, relative to previous results, by a detailed study of, and a resultant derived correction for, the influence of the sugar exocyclic group conformation on the chemical shifts of the sugar ring protons. This was achieved with the aid of nucleosides and nucleotides fixed in the conformations gauche-trans [derivatives of 8,5'-(R)-cyclo] and trans-gauclze [derivatives of 8,5'-(S)-cyclo]. The results of 13C NMR confirmed those obtained by 'H NMR. The measured values of the vicinal coupling constants between H-1 ' and the C-8 and C-4 carbons were employed to evaluate approximately the glycosidic angles x of the nucleosides in the conformations s,yn and anti. A critical examination is made of the applicability of relaxation methods, involving analysis of spin-lattice relaxation time of protons ( T I ) and the Overhauser effect, to determine the conformation of the base about the glycosidic bond; interpretations are provided for the lack of agreement between these methods and those based on chemical shifts in the present study. The foregoing results are also applied to an examination of the effect of the conformation of the base about the glycosidic bond on the enzymatic reactions catalyzed by 5'-nucleotidase and adenosine deaminase.
European Journal of Biochemistry, 1974
The water proton relaxation times, TI and T2, have been measured in solutions of free Gd(II1) ions and in Gd(II1) solutions containing lysozyme over a wide range of temperatures (0-40 "C) and nuclear frequencies (4 -60 MHz) using pulsed nuclear magnetic resonance techniques. The equilibrium between lysozyme and Gd(II1) has also been studied as a function of temperature. Water relaxation rates in both the free and enzyme-bound metal sites have been determined and closely fitted to existing theories over the complete range using a combination of graphical and computing techniques. Values for the water co-ordinat'on number ( 4 ) and the correlation time (tc) for the dipolar relaxation processes have been obtained and the rate processes contributing to zc have been analysed as a function of temperature and frequency. The values obtained for zc in the enzyme complex differ considerably from some earlier estimates. In the aquo-ion relaxation is dominated by the rotational correlation time (ZR) but in the enzyme-metal complex the electron spin relaxation time (z,) becomes more important than other processes at low frequencies. Possible sources of error in the data and assumptions made in the theoretical treatment are discussed. The implications of the results for mapping studies of lysozyme and other macromolecules, using magnetic resonance techniques, are stressed.
Magn Reson Chem, 1981
The relationship between vicinal N M R proton-proton coupling constants and the pseudorotational properties of the sugar ring in nucleosides and nucleotides is reinvestigated. Compared with our earlier study several important improvements are introduced: first, a new empirical generalization of the classical Karplus equation is utilized, which allows an accurate correction for the effects of electronegativity and orientation of substituents on 3J(EIH); second, empirical correlations between the parameters governing the conformation of p-D-furanosides (taken from an analysis of 178 crystal stmctores) were used to define proton-proton torsion angles as a fnnctiou of the pseudorotation parameters P and a,,,; and, third an iterative least-squares computer program was devised to obtain the best fit of the conformational parameters to the experimental coupling constants. N M R data for the sugar ring in the following compounds were taken from the literature and analysed: 3',5'-cy&c nudeotides, a base-stacked nionucleotide, 2'-~ydroarabinonucleosides, or-~-2',2-0-cyclouridine, 2'-and 3'-aminosubstituted ribonucleosides, 2'-and 3'-deoxyribonucleosides. The present results confirm that the conformational properties found in the solid state are, on the whole, preserved in solution.
Selective and nonselective proton spin-lattice relaxation studies of enzyme-substrate interactions
Journal of Magnetic Resonance (1969), 1982
The selective and nonselective longitudinal relaxation rates were measured for glycyl-r-tyrosine protons in the presence of Zn-carboxypeptidase A. Unlike the nonselective relaxation rates, the selective rate was found to be particularly sensitive to the presence of the enzyme. From the nonselective/selective ratio, the correlation times of the free and bound substrate were evaluated.
Journal of the American Chemical Society, 1978
A procedure is described by which a structure of molecular complex in solution is found when one of the interacting molecules is a free radical. The method is based on measurements of unpaired-electron induced nuclear magnetic relaxation, and can apply to a system involving a free radical whose unpaired electron is delocalized over the molecular framework. The method was first applied to a system of adenosine 5'-monophosphate (5'-AMP) and ,V-methqlphenazinium cation radical (MPH+.) in a neutral D20 solution. The experimental procedures are described to obtain the association constant, the rotational correlation time, and the averaged electron-nuclear distances in the complex. A process of computer-assisted search for probable structures of the complex is described, which is based on the comparison of the experimental electron-nuclear distances with those calculated for essentially all possible mutual orientations of the two molecules and the internal rotations by taking the distribution of the unpaired electron in the free radical explicitly into account. I t is shown that all allowed structures of the complex between 5'-AMP and MPH+. are such that two K planes are nearly parallel with a plane-to-plane distance of 3.0-3.5 A. The best agreement between the experimental and the calculated distances is obtained when S'-AMP takes an anti conformation and the long axes of the two T planes of 5'-AMP and MPH+. orient nearly perpendicular to each other. This orientation of the two rings was supported by the simple consideration of intermolecular forces.
Measurement of solute proton spin-lattice relaxation times in water using the 1,3,3,1 sequence
Magnetic Resonance in Medicine, 1986
1H NMR spin-lattice relaxation times (T1) of the NCH3 proton resonances of phosphocreatine (PCr) and creatine (Cr) in water solutions were obtained using the 1,3,3,1 pulse sequence. These T1 values were equivalent to those obtained in D2O and water using either the conventional inversion-recovery experiment or the 1,3,3,1 pulse sequence. Thus, the 1,3,3,1 sequence of proton NMR can provide an independent means along with phosphorous NMR for assess PCr and for the study of the creatine kinase reaction (PCr + ADP ⇌ ATP + Cr) in aqueous solutions and perhaps in biological preparations. © 1986 Academic Press, Inc.