Burton, Stephanie G. and Don A. Cowan. NEW BIOTRANSFORMATIONS FOR OXIDATION PROCESSES
Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, E. Cape 6140 South Africa (s.burton@ru.ac.za)
Oxidative biotransformations, particularly those not requiring expensive cofactors but instead utilising oxygen or peroxide, are particularly useful industrially, and are receiving increasing attention in the field of biocatalysis. The purpose of such biotransformations can be to produce compounds with significant economic value, or to remove them from effluents and convert them to less toxic forms. Valuable antioxidant compounds can be produced as food additives, pharmaceuticals, or nutraceuticals.
This paper describes biotransformation systems catalysing oxidation reactions on novel substrates. Polyphenol oxidase catalyses the ortho-hydroxylation of a wide range of phenolic compounds to catechols and on to ortho-quinone products, and peroxidase and laccase, catalyse oxidations yielding free radicals which can subsequently be further reacted. Utilisation of these enzymes allows functionalisation of many unreactive substrates to produce more reactive synthons. In recent developments, laccase and oxidase enzymes produced by novel bacterial isolates have been used to produce vanillic acid and vanillin.