Approach for the Simultaneous Flow Injection Determination of L-Tyrosine and L-Lysine based on the Enzyme Reactors

The simultaneous determination of L tyrosine and L lysine, by enzyme supported flow injection analysis (FIA) was developed using two enzyme reactors in parallel and a single oxygen electrode. L-Tyrosine and L-lysine were determined using the enzyme Ltyrosinase (EC 1.14.18.1) and L-lysineLY -oxidase (LysOD, EC 1.4.3. -), respectively. When sample solutions were simultaneously injected into the two reactors (the tyrosinase reactor and the LysOD reactor) with a controlled residence time, a “train” of two peaks corresponding to L-tyrosine and r_-lysine were seen in the FIA-gram. The peak currents were linearly related to the L-tyrosine and L-lysine concentration in the range of 0.1-0.8 mM and 0.05-0.5 mM, respectively. The present system was applied to the determination of L-tyrosine and r_-lysine in the synthetic mixture.