The salt-induced destacking of purine in aqueous sodium chloride systems and its implications on life at elevated temperatures

Abstract

Aqueous purine solutions in the absence and presence of NaCl were studied by vapor-pressure osmometry and high-resolution PMR spectroscopy. The presence of NaCl causes a marked change in the temperature dependence of the molal osmotic coefficient and the chemical shift of the purine resonances when compared with the corresponding quantities in purine solutions containing no added salt. In the absence of salt, the destacking of the purine is gradual as the temperature is increased, whereas there is a sharp decrease in purine stacking at .apprx.42.degree. C in the presence of NaCl. This salt-induced destacking of purine is consistent with the previously noted salt-induced bulk water destructuring at temperatures above .apprx.42.degree. C. This effect was deduced from considerations of species profiles in acid-water systems as a function of temperature. The implications of this phenomenon on biological systems at elevated temperatures are discussed.