title: Development of a multienzyme reactor for dopamine synthesis: I. enzymology and kinetics.
abstract: The enzymology and kinetics of tyrosine phenol lyase (TPL) from Erwinia herbicola, and tyrosine decarboxylase (TDC) from Streptococcus faecalis have been investigated for potential use in a coimmobilized multienzyme biocatalytic system for the production of dopamine. In this multienzyme biotransformation using whole cells optimized for each of the respective enzymes, TPL catalyzes the production of 3,4-dihydroxyphenyl-L-alanine (L-dopa) from catechol, pyruvate, and ammonium, and this is subsequently decarboxylated by TDC to produce dopamine. Performing the reactions simultaneously, thereby removing L-dopa, is one option for overcoming the TPL equilibrium constraints. The enzymes have different optimal pH values, so the reaction kinetics at a compromise pH of 7.1, where both enzymes could be operated simultaneously, were investigated. For the concentration range investigated, TPL followed pseudo-first-order kinetics with respect to catechol, pyruvate, and ammonium. TDC exhibited significant product inhibition as well as inhibition by combinations of catechol and pyruvate.
authors.affiliation: Biochemical Engineering Group, Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: W A
authors.initials: WA
authors.lastname: Anderson
authors.forename: M
authors.initials: M
authors.lastname: Moo-Young
authors.forename: R L
authors.initials: RL
authors.lastname: Legge