A MULTINUCLEAR NMR-STUDY ON THE MICROSCOPIC IONIZATION-CONSTANTS OF ADENOSINE-5'-TRIPHOSPHATE IN AQUEOUS-SOLUTION

A H-1, C-13 and P-31 NMR study of adenosine-5'-triphosphate has been performed as a function of pH. The examination of the chemical shifts allowed the proposal of an ionization scheme in which the third deprotonation takes place both on the adenine ring and on the phosphate group in a ratio of about 2:1. Furthermore, an analysis of carbon relaxation times supports this mechanism of ionization and confirms that the adenine ring binds the proton both on the NH2 group and the N7 nitrogen atom.