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Stabilizing effectiveness of alkali metals toward ribonucleic acid from the bacterial virus R17
Author(s) -
Gordon Julius A.
Publication year - 1965
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360030103
Subject(s) - chemistry , alkali metal , solubility , salt (chemistry) , phosphate , aqueous solution , inorganic chemistry , ionic strength , hofmeister series , rna , uracil , metal , organic chemistry , biochemistry , dna , gene
The addition of alkali metal cations (0.10–1.00 M ) stabilizes the macromolecular structure of R17‐RNA as evidenced by a shift of the optical density–temperature profiles to higher temperature. This effectiveness is found to decrease in the order Li + > Na + > K + > Rb + > Cs + and the midpoints of each profile ( T m ) are found to increase linearly for each salt with the log of the salt concentration. The differences in effectiveness in this series can be best interpreted as a decreasing specific interaction of Li + , Na + , K + , and Rb + with the phosphate groups of RNA as suggested by known binding constants to phosphate groups and the failure of adenine, adenosine, adenine monophosphoric acid, and uracil to show specific solubility differences in these salts. The importance of this feature is that the thermal stability of RNA in the presence of alkali metals shows specific ion requirements in addition to general electrostatic interactions. Furthermore, the more nonspecific, ionic strength‐dependent stabilization of native RNA also involves a decrease in adenine solubility (e.g., increased activity) and an increase in phosphate solubility in the aqueous salt solutions in addition to the well recognized Coulombic shielding of the negatively charged phosphates.