Tagatose is a rare hexoketose with potential health benefits. Here, an enzyme, GatZ subunit ofd-tagatose-1,6-bisphosphate aldolase, was characterized. GatZ is involved in a multi-enzyme cascade reaction system that can produce tagatose from maltodextrin. It showed maximum activity at 70 °C and a pH 8.0, and required supplementation with 5 mM Mg2+ to achieve the highest catalytic activity. The Km and Vmax values of GatZ using fructose 6-phosphate as substrate were 5.66 mM and 0.0329 mmol/L min, respectively. An in vitro multi-enzyme system containing GatZ was constructed, and 1.75 g/L tagatose was produced from 5 g/L maltodextrin after 10 h. This biosystem could potentially enrich the application of C4 epimerases in rare sugar bioproduction.
Keywords: C4 epimerization; Fructose; Maltodextrin; Tagatose.
Copyright © 2020 Elsevier Inc. All rights reserved.