Electrochemical behaviour of mono- and oligonucleotides and the corresponding nucleosides Part VI. Comparative voltammetric study on the adsorption of 1-β-D-arabinofuranosylcytosine and 1-β-D-ribofuranosylcytosine at charged interfaces

Abstract

Cytostatic actions of 1-β-D-arabinofuranosylcytosine have been reported. Therefore a systematic comparative study was undertaken on the adsorption and association of 1-β-D-arabinofuranosylcytosine (ara-C) and 1-β-ribofuranosylcytosine (r-C) in acid and neutral solution at the mercury-solution interface constituting a model for charged biological interfaces in the living cell with respect to the biophysicochemical behaviour of the studied nucleosides. The adsorption was followed by out-of-phase a.c. voltammetry and by single sweep voltammetry at the hanging mercury drop electrode (HMDE). Characteristic properties and adsorption parameters of the dilute and compact adsorption layers of ara-C and r-C were evaluated from the obtained double step Frumkin isotherm and from the potential dependence of adsorption. While the properties in the dilute layer are rather similar for both, ara-C and r-C, the compact layer of ara-C is more dense indicating a substantial influence of the different steric arrangement in the sugar moiety of both otherwise similar nucleosides. The importance of the obtained results for the biochemical behaviour at natural charged surfaces is discussed.