No abstract

No abstract

Thin-layer electrochemical techniques were developed for measuring E°' and n-values of biological redox systems. A spectropotentiostatic method combines optical measurements of the biocomponent with potential control of a thin solution layer. Coupling of the biocomponent to the electrode potential is achieved by chemical modification of the electrode or by addition of a mediator-titrant. The temperature dependence of E°' is determined easily. This condition is exemplified by cytochrome c for which measurements were sufficiently precise to resolve a nonlinear behavior in the E°' temperature dependence. Biocomponents with no observable optical properties can be studied by thin-layer pulse coulometry and thin-layer staircase coulometry. In these techniques, E°' and n are determined by measuring charge as a function of potential. The activity of galactose oxidase was measured while simultaneously controlling its oxidation state. The oxidation state is controlled by a gold electrode (coupled with ferricyanide as a mediator-titrant) in a thin-layer cell with a peroxide electrode inserted in one side. The relative activity of the enzyme is monitored by measuring peroxide production from the enzyme-catalyzed reaction of substrate. Thin-Layer Cells