An enzyme electrode for specific determination of L ‐lysine: A real‐time control sensor

Lysine decarboxylase ( L ‐lysine carboxylyase, E.C.4.1.1.18) is immobolized on a carbon dioxide gas‐sensing electrode, by copolymerization with gelatin using the bifuncitional agent glutaraldehyde. The enzyme electrodes thus prepared are used in a continuous flow system to measure the concentration of L ‐lysine in a mixture of amino acids. The measuring time for each sample is about 3 min, including response and rinsing times. The electrode response is linear between 0.01‐1 g/L and has a high specificity for L ‐lysine. The enzyme electrode response to lysine at concentrations below 0.5 g/L is stable on repeated use for at least 500 assays.