NEW DATA ON THE CONFORMATION OF NUCLEOSIDE 5'-DI-TRIPHOSPHATES AND 5'-TRIPHOSPHATES OBTAINED BY ROESY EXPERIMENTS

The conformation and flexibility of four nucleotides commonly used as ATPase substrates, ADP, ATP, AMPPCP, and AMPPNP, have been investigated by using ROESY and T2 experiments, in the absence and presence of Mg ions. This work, based on ROESY techniques, provides new data about the conformation of nucleosides 5′-di- and 5′-triphosphates. It is shown that ADP exhibits a conformation similar to that observed for the nucleoside 5′-monophosphates8,11 and that, in contrast, one particular conformational region is predominant for the nucleoside 5′-triphosphates: in the presence of a third phosphate group, high anti conformations are predominant. The data relative to AMPPCP indicate that this base conformation is associated with a base-phosphate stacking, which could be a general feature of the nucleoside 5′-triphosphates. T2 measurements at two frequencies and concentration dependence ROESY experiments show that the conformational properties derived from ROESY spectra are due to intramolecular interactions and, in addition to NOE and ROE values, suggest that a model of an isotropic motion governed by a single Tc is not sufficient to characterize the molecular dynamics of the nucleosides triphosphates. © 1990, American Chemical Society. All rights reserved.