Electrochemical sensing for the determination of activated cyclic AMP-dependent protein kinase

A novel electrochemical system has been developed for monitoring the cyclic AMP-dependent protein kinase (PKA) activity. In this method, PKA activity was monitored as the change in the redox current of a ferrocene-pendant PKA substrate peptide (Fe-LRRASLG) on a gold electrode, which had been modified with thioctic acid, using cyclic voltammetry. The phosphrylation of the ferrocene-pendant substrate with PKA changed the net charge from +1 to -1. This caused a decrease in the redox current of the ferrocene unit due to an electrostatic repulsion between the substrate and the anionic surface of the electrode. We expect that this method is potentially useful for monitoring the enzyme activity in medical or pharmacological fields.