306 - Nucleotides and related substances: Conformation in solution and at solution|electrode interfaces

Abstract

The problems involved in inferring conformation and orientation from electrochemical measurements are considered as are the implications of extrapolating the results for relatively simple nucleotides to biopolymers. The determination of conformation, e.g., shape in solution -- more particularly, when approaching the electrode -- largely depends on estimation of the effective molecular cross-section as reflected in the experimentally measured diffusion coefficient, D; for example, formation of associated species as in base stacking is usually reflected in a variation in D and, often, in redox potential. The determination of conformation at the solution|electrode interface is often intimately connected with the state and orientation of an adsorbed species -- more particularly of its electroactive and adsorption sites -- relative to the electrode surface. Current trends in inferring such interfacial conformation for DNA and derived large nucleic acid species are summarized; the adsorption pattern seen on oxidation of NADH at carbon electrodes is reviewed.