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Georgia Journal of Science

Abstract

Guanosine 5'-triphosphate (GTP) plays a pivotal role in many biologi­cal processes. The interactions of cations with GTP are essential to the stabilization of this nucleotide and the regulation of its functions. In this study, we present solution 31P NMR data on GTP samples in varied salt concentrations or pHs. From chemical shifts and T1 , T2 relaxations, it is concluded that the interaction strengths of cations with GTP are in the order of Ca2+ > Mg2+ > Li+ > Na+ for the cations, and in the order of beta > gamma > alpha for the phosphate groups. An increased sample pH causes deprotonation of the beta and gamma phosphates with enhanced cations' affinities, as indicated by significant chemical shift changes, while the chemical shift of alpha phosphate is essentially unaf­fected by varying pH. These results will aid in exploring the mecha­nism of GTP-cation interactions, and fully understanding the effects of cations on GTP's stabilization and its biological activities.

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