Evidence that the putative α‐glucosidase of Thermotoga maritima MSB8 is a pNP α‐D‐glucuronopyranoside hydrolyzing α‐glucuronidase

Abstract
The gene (agu) encoding p‐nitrophenyl α‐D‐glucuronopyranoside (pNP‐GUA) hydrolyzing α‐glucuronidase of the hyperthermophilic bacterium Thermotoga maritima was cloned and expressed in Escherichia coli. The recombinant enzyme was purified and characterized. The gene previously designated as putative α‐glucosidase was found to code for a protein that had no α‐glucosidase activity. It showed a rare activity profile with its ability to hydrolyze pNP‐GUA, an activity not known in the α‐glucuronidases from microbial sources. This is the first report on the occurrence of an α‐glucuronidase which belongs to the family 4 of glycosyl hydrolases.