Optimal catalyst distribution in a dual enzyme sequential system

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Abstract
The dual enzyme sequential reactions that decompose arginine to ammonia were investigated experimentally to determine appropriate rate equations and to test predictions of optimal distribution of the two enzymes (arginase and urease) immobilized in a packed‐bed reactor.The kinetics of this system were experimentally found to be of the kind that calls for a bang‐band control with a well‐defined switching point between the two immobilized enzyme catalysts. At low values of reactor residence time, the optimum switching point is shown to approach a limiting position which depends on the kinetic order of the second reaction. In the higher ranges of residence time, the switching point moves into the latter half of the reactor, but exceptions to this generalization are found when Michaelis‐Menten kinetics are applicable to both reactions. For the special circumstance where the two reactions are of zero and first order, respectively, the optimal distribution of the two catalysts is independent of the first rate constant. The experimental results are, in general, consistent with these expectations, and secondary deviations are discussed. A suboptimal policy alternative is also treated analytically and tested by experiment.
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