Process properties of an l-amino acid oxidase from Hebeloma cylindrosporum for the synthesis of phenylpyruvic acid from l-phenylalanine.

• Oxidation of an l -amino acid using a recombinant l -amino acid oxidase from Hebeloma cylindrosporum was studied. • Properties of this enzyme were determined for the formation of phenylpyruvic acid from l -phenylalanine as a model reaction. • The enzyme displayed a reasonable operational stability in the reaction system. • Promising applicability data with respect to substrate and product inhibition were found. • In a biotransformation, 20 mM of substrate were converted after 4 h reaction. The biocatalytic oxidation of amino acids represents an attractive approach towards the synthesis of α-keto acids, which are interest for various industrial applications. As l -amino acids are readily available from fermentation processes, these natural amino acids can serve as substrates in combination with an l -amino acid oxidase. Besides an aqueous phase as reaction medium, a further advantage of such a process is the utilization of air as oxidation agent. In this study, we studied the organic-synthetic properties of a literature-known recombinant l -amino acid oxidase from the fungus Hebeloma cylindrosporum with respect to its suitability to catalyze the formation of α-keto acids exemplified for the synthesis of phenylpyruvic acid starting from l -phenylalanine as a substrate. In our study the enzyme displayed a reasonable operational stability in the reaction system and as well as promising applicability data with respect to substrate and product inhibition. In a biotransformation, 20 mM of substrate were converted after 4 h reaction. The formation of undesired by-products was suppressed using a commercially available catalase enzyme. [ABSTRACT FROM AUTHOR]