A Thermostable Non-xylanolytic α-Glucuronidase of Thermotoga maritima MSB8

抄録

  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-O-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 higher identity with Agu4A (another α-glucuronidase of T. maritima, 61%) than with AglA (α-glucosidase of T. maritima, 48%).