Determination of phenolic compounds using recombinant tyrosinase from Streptomyces antibioticus

Properties of Streptomyces antibioticus tyrosinase and the implementation o f the enzyme in a biosensor for the detection of phenolic compounds were in vestigated. The tyrosinase from S. antibioticus is a monomer and has a mole cular weight of 30.6 kD. The specific activity is about 5 U/mg with catecho l as substrate and 1225 U/mg with L-dopa as substrate. The activity of tyro sinase upon long-term storage is best maintained in buffer at temperatures of -80 or +4 degreesC. Storage at -18 degreesC, with or without glycerol, r esulted in quick enzyme inactivation. For the construction of the sensor bi-enzymatic substrate recycling was exp loited. Quinoprotein glucose dehydrogenase (GDH) and tyrosinase were immobi lised in polyvinyl alcohol and coupled to a Clark-type oxygen electrode tha t allowed for monitoring of the oxygen consumption during catechol conversi on. This design of the sensor facilitates the determination of phenolic com pounds in the nanomolar range. The lower limit of detection for L-dopa, dop amine, and adrenalin was 5 nM. (C) 2001 Elsevier Science B.V. All rights re served.