Na-23 Solid-state NMR studies of hydrated disodium adenosine triphosphate

The biologically important compound hydrated disodium adenosine 5'-triphosp hate (ATP) was studied focusing on the Na-23 nucleus (spin quantum number I = 3/2) as probe in various solid-state NMR techniques including magic-angl e spinning (MAS), cross-polarization MAS (CPMAS) and multi-quantum MAS (MQM AS) at 4.7 and 9.4 T. MQMAS experiments enabled the resolution of all the f our crystallographically different Na-23 sites in the unit cell in the MQMA S spectrum at 4.7 T, but not at 9.4 T. The four sites were successfully ass igned and the principal elements of the quadrupolar tensors and isotropic c hemical shifts of the Na-23 nuclei at each lattice site determined by analy zing and computer simulating the above experimental spectra. (C) 2000 Elsev ier Science B.V. All rights reserved.