Enzyme Amplification for Trace Level Determination of Pyridoxal 5'-Phosphate with a pCO2 Electrode

Article abstract of DOI:10.1021/ac00226a029

A highly sensitive and selective potentiometric method for the determination of the enzymatically active form of vitamin B₆, pyridoxal 5'-phosphate (PLP), has been devised.The method is based upon the decarboxylation of L-tyrosine by the apoenzyme tyrosine decarboxylase in the presence of PLP, using a pCO2 electrode to monitor the reaction rate.Under optimized conditions, an amplification factor of up to 1E5 is achieved, and PLP levels as low as 1E-9 M can be measured with good precision and an analysis time of only 20 min.Other members of the vitamin B₆ group and their phosphate derivatives do not interfere with the proposed method.