Horseradish peroxidase (HRP), an enzyme omnipresent in biotechnology, is still produced from hairy root cultures, although this procedure is time-consuming and only gives low yields. In addition, the plant-derived enzyme preparation consists of a variable mixture of isoenzymes with high batch-to-batch variation preventing its use in therapeutic applications. In this study, we present a novel and scalable recombinant HRP production process in Escherichia coli that yields a highly pure, active and homogeneous single isoenzyme. We successfully developed a multi-step inclusion body process giving a final yield of 960 mg active HRP/L culture medium with a purity of ≥99% determined by size-exclusion high-performance liquid chromatography (SEC-HPLC). The Reinheitszahl, as well as the activity with 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 3,3',5,5'-tetramethylbenzidine (TMB) as reducing substrates, are comparable to commercially available plant HRP. Thus, our preparation of recombinant, unglycosylated HRP from E. coli is a viable alternative to the enzyme from plant and highly interesting for therapeutic applications.
Keywords: E. coli; hydrophobic interaction chromatography; inclusion bodies; recombinant horseradish peroxidase; refolding; reversed-phase high-performance liquid chromatograpy (RP-HPLC); size exclusion HPLC (SEC-HPLC).