Electrostatic potential modulations on polynucleotides as a function of ionic content: potentiometric determinations.
Open Access
- 1 May 1976
- journal article
- Published by Oxford University Press (OUP) in Nucleic Acids Research
- Vol. 3 (5) , 1373-1386
- https://doi.org/10.1093/nar/3.5.1373
Abstract
PK values of ionisation of cytidine residues, in poly C and poly I. poly C, have been determined by potentiometric titration as a function of either ionic strength (Na$) or Mg2$ concentration. The results are interpreted as a consequence of the existence of a local pH, prevailing in the vicinity of the polynucleotides, smaller than that of the bulk solution. This local pH is dependent upon the electrostatic potential Ψ due to the negatively charged phosphate groups of the polynucleotide. Moreover Ψ can be modulated through variation of either ionic strength or Mg2$ concentration. At a given pH Mg2$ addition leads to the release of protons which, in the case of complex systems of limited stability, might be detected by the use of the pH-stat method. Possible functional implications for genetic translation systems are examined.Keywords
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