The temperature-dependent self-association of adenosine 5'triphosphate in 0.154 M NaCl.

The disodium salt of adenosine 5'triphosphate (ATP), dissolved in and dialyzed against isotonic saline, undergoes a temperature-dependent self-association. Self-association increases with decreasing temperature. The technical achievement that made these experiments possible was the development and availability of a hollow fiber dialyzer with a low molecular weight (200) cutoff. Several models were tested to describe the experimental data, and a monomer-dirner-trimer association seemed to describe the data best- Both the dimerization and trimerization were exothermic; values of the thermodynamic functions for these reactions are reported. The self-association reaction for ATP is much stronger than that observed for purine and cyridine, as well as for various nucleosides whose self-association in aqueous solutions has been studied.