CONSTRUCTIONOFAN FIA UNIT AND ITS USE IN THE INVESTIGATION OF IMMOBILISED LIGNIN PEROXIDASE

Abstract

A flow injection analyser was designed to serve asa tool for the characterisation of enzymes. The original device was constructed from available laboratory equipment, and has subsequently been refined to a fully automated, stand alone unit. The hard- and software have been so conceived as to enable a wide range of applications. All system components are controlled by a microprocessor, which also takes over data acquisition, peak integration and evaluation, and provides a convenientinterface to the user via a key-board and display. We have used this FIA system to investigate the enzymatic properties of lignin peroxidase. This enzyme is believed to play a key role in the biodegradation oflignin by white-rot fungi, and has attracted interest for use in various industrial processes. Lignin peroxidase has a very similar mechanism of action to horse radish peroxidase, butdiffers in its ability to oxidise organic compoundsof higher oxidation potential, and in its extreme sensitivity to inactivation by excess H2O2. The enzyme can be successfully immobilised on a variety of carriers. However when investigated in batch assays, the loss of activity is such that repeated experimentation is impossible. FIA is characterised by small sample volumes, and thus low contact times when working with an immobilised enzyme. We have exploited this to enable investigation of an essentially unstable enzyme system.