Development of a multienzyme reactor for dopamine synthesis: II. Reactor engineering and simulation

Aspects of reaction engineering associated with multienzyme reactions have been studied in a system where dopamine is produced from catechol, pyruvate and ammonium by sequential enzymatic reactions catalyzed by tyrosine phenol lyase (TPL) and tyrosine decarboxylase (TDC). Microbial cells containing TPL activity (Erwinia herbicola) and TDC activity (Streptococcus faecalis) were coimmobilized in glutaraldehyde cross-linked porcine gelatin beads with a mean diameter of 2.8 mm for use in the reactions. Measurement of the transport properties in the beads indicate that the gelatin matrix does not significantly increase the diffusion resistance and that dopamine partitions into the matrix (K = 2). A packed-bed reactor containing the coimmobilized cell beads successfully produced dopamine, although with a low conversion. Using computer simultaneous it is shown that separate, sequential TPL and TDC, rather than simultaneous, reactions, would require smaller reactors overall for the same conversion.