A thermostable non-xylanolytic α-glucuronidase of Thermotoga maritima MSB8

Abstract

A putative α-glucosidase belonging to glycosyl hydrolase family 4 of Thermotoga maritima (TM0752) was expressed in Escherichia coli and it was found that the recombinant protein (Agu4B) was a p-nitrophenyl α-D- glucuronopyranoside hydrolyzing α-glucuronidase, not α-glucosidase. It did not hydrolyze 4-0-methyl-D-glucuronoxylan or its fragment oligosaccharides. Agu4B was thermostable with an optimum temperature of 80°C. It strictly required Mn2+ and thiol compounds for its activity. The presence of NAD+ slightly activated the enzyme. The amino acid sequence of Agu4B showed hmgher identity wmth Agu4A (another α-glucuvonidase of T. maritima, 61%) than with AgIA (α-glucosidase of T. maritima, 48%).