ENZYME ELECTRODE-BASED KINETIC ASSAYS OF ENZYME-ACTIVITIES

Potentiometric enzyme electrodes for urea, AMP, and adenosine have been used for the kinetic assays of arginase (EC 3.5.3.1.), 3′:5′-cyclic-nucleotide phosphodiesterase (EC 3.1.4.17), and 5′-nucleotidase (EC 3.1.3.5), respectively. The initial rate of potential change, after addition of the enzyme to the substrate solution, is direetly proportional to the enzyme activity present. Arginase assays were found to be reproducible to a relative precision of 13% or better and applicable to the direct measurement of arginase activity in beef liver homogenates. © 1979.