Imaging the activity of nitrate reductase by means of a scanning electrochemical microscope

Scanning electrochemical microscopy (SECM) was used to characterize immobil ized nitrate reductase (NaR) from Pseudomonas stutzeri (E.C. 1.7.99.4). Nit rate reductase with membrane fragment was embedded in a polyurethane hydrog el in a capillary and solubilized NaR without membrane fragment was covalen tly coupled to a diaminoethyl-cellulose-carbamitate film on glass. After sy stematic studies of possible mediators, SECM feedback imaging of both forms of immobilized NaR was accomplished with methylviologen as redox mediator.