The role of molecular interaction between GOD and metal complexes on redox mediation processes

In this work, we study the redox mediation of glucose oxidase (GOD) with a series of Co(II) polypyridine complexes [CoIIL3]2+ (L = 5-Nitro-1,10-phenanthroline, 5-Chloro-1,10-phenanthroline, 5-Bromo-1,10-phenanthroline, 1,10-phenanthroline and 5-methyl-1,10-phenanthroline) and Ferrocenecarboxylic acid (Fc-COOH), in order to understand the role of molecular interaction GOD-mediator on homogeneous electron transfer rate constant (ks), exploring Marcus cross-relation and tunneling effect model, not reported before. The ks values were calculated through a foot of the wave analysis (FOWA) from cyclic voltammetry data. Circular Dichroism spectroscopy reveals no structural changes in the enzyme in the presence of the redox mediators. The interaction energy between GOD and Co(II) complexes and a series of ferrocene derivatives (FcCOOH, Fc-CH2NH(CH3)2, Fc-1,1-CH3, Fc-CH CH2, and Fc) was calculated using DFT and molecular docking. Quantitative Structure-Activity Relationship (QSAR) analyses were explored to rationalize ks values with theoretical calculations. The results allow us to propose that the GOD-mediator interaction, should be considered for a better description of the electron transfer process, useful for potential bioelectronic applications.