High-resolution study of nuclear magnetic relaxation dispersion of purine nucleotides: effects of spin-spin coupling.
By combining magnetic field cycling in the range from 0.1mT to 7T 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 site-specific 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.
Kiryutin
Alexey
A
Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
Ivanov
Konstantin
K
Yurkovskaya
Alexandra
A
Vieth
Hans-Martin
HM
D000249:Adenosine Monophosphate / Q000737:chemistry; D006157:Guanosine Monophosphate / Q000737:chemistry; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D011522:Protons; D011685:Purine Nucleotides / Q000737:chemistry*; D012266:Ribose / Q000737:chemistry
D011522:Protons; D011685:Purine Nucleotides; D000249:Adenosine Monophosphate; D012266:Ribose; D006157:Guanosine Monophosphate