Interfacial behavior of adenine and its nucleosides and nucleotides

Abstract

The adsorption of adenine, adenosine and AMP has been studied by surface electrochemical methods at pH 8.0. All compounds exhibit an initial or dilute adsorption region where they are probably adsorbed with the base flat on the electrode surface. It is proposed that adenosine and AMP adopt the syn conformation so that the sugar or sugar phosphate moiety, respectively, is largely rotated out of the plane of the electrode and the base residues can pack together almost as closely as the free bases. At potentials centered at −0.5 V and bulk solution concentrations≥ ca. 3 m M adenine appears to undergo a surface reorientation and adopts a perpendicular stance. In this new orientation it is proposed that adenine is bound to the electrode through its amino group hydrogen atoms forming a [Display omitted] |-electrode hydrogen bond. Adenosine appears to form two types of perpendicular layers. At small positive electrode charges it is suggested that it adopts an anti conformation and is adsorbed with the negative end of its permanent dipole directed towards the electrode. At more negative potentials it is proposed that adenosine retains the anti conformation but is adsorbed with the positive end of its dipole directed towards the electrode