METHIONINE SELECTIVE ENZYME ELECTRODE

A potentiometric enzyme electrode is described for the direct assay of free methionine in solution. An enzyme, methionine lyase, was successfully purified from P. ovalis. Among 22 naturally occuring amino acids, the final preparation catalyzed only L-methionine to liberate NH3. The immobilized enzyme Is stable for 3 months, with no loss of activity, exhibits a linear response to L-methionine over the range of 10-2 to 10-5 M. The optimum conditions for the measurement and for storage of the electrode have been evaluated. No interference from the common amino acids was observed. © 1979, American Chemical Society. All rights reserved.