In vivo cascade catalysis of aromatic amino acids to the respective mandelic acids using recombinant E. coli cells expressing hydroxymandelate synthase (HMS) from Amycolatopsis mediterranei

Abstract

Mandelic acids are valuable products which are used in a broad field of applications. The enzyme hydroxymandelate synthase (HMS) is a non-heme iron dioxygenase which converts para-hydroxyphenylpyruvate and other 3-aryl pyruvates by decarboxylation to the corresponding mandelates. In the present work, the gene hms encoding the hydroxymandelate synthase from Amycolatopsis mediterranei was cloned and overexpressed in Escherichia coli BL21(DE3) for in vivo cascade catalysis taking advantage of resident aromatic amino acid transaminases. The resulting recombinant cells were used for whole cell biotransformations. We successfully accomplished the production of para-hydroxymandelate exclusively by using the aromatic amino acid l-tyrosine in biotransformation. Furthermore, by utilizing different phenylalanine derivatives (including chloro-, fluoro- and hydroxylated amino acids), the corresponding S-mandelic acids were obtained with high conversion (21–87 %) and high ee (38–97%). This process is an alternative and attractive way to get access to a variety of mandelic acids.