The α-D-Glucuronidase test kit is a simple, reliable and accurate method for the measurement and analysis of α-D-glucuronidase in various enzyme preparations. The kit contains a pure aldotriouronic acid substrate and an α-D-glucuronidase (GH67) control enzyme.

Suitable for manual and microplate formats.

New, improved substrate.

This kit contains highly purified, borohydride reduced aldotriouronic acid with a terminal α-D-glucuronic acid substitution, which is an excellent substrate for α-D-glucuronidases from GH67. This substrate can be also used for the measurement of α-D-glucuronidases from GH115, however the rate of hydrolysis compared to GH67 is reduced. Previously this kit contained a mixture of borohydride reduced aldouronic acids (tri:tetra:penta).

Evidence that GH115 α-glucuronidase activity, which is required to degrade plant biomass, is dependent on conformational flexibility.

Rogowski, A., Baslé, A., Farinas, C. S., Solovyova, A., Mortimer, J. C., Dupree, P., Gilbert, H. J. & Bolam, D. N. (2014). Journal of Biological Chemistry, 289(1), 53-64. Link to Article Read Abstract The microbial degradation of the plant cell wall is an important biological process that is highly relevant to environmentally significant industries such as the bioenergy and biorefining sectors. A major component of the wall is glucuronoxylan, a β1,4-linked xylose polysaccharide that is decorated with α-linked glucuronic and/or methylglucuronic acid (GlcA/MeGlcA). Recently three members of a glycoside hydrolase family, GH115, were shown to hydrolyze MeGlcA side chains from the internal regions of xylan, an activity that has not previously been described. Here we show that a dominant member of the human microbiota, Bacteroides ovatus, contains a GH115 enzyme, BoAgu115A, which displays glucuronoxylan α-(4-O-methyl)-glucuronidase activity. The enzyme is significantly more active against substrates in which the xylose decorated with GlcA/MeGlcA is flanked by one or more xylose residues. The crystal structure of BoAgu115A revealed a four-domain protein in which the active site, comprising a pocket that abuts a cleft-like structure, is housed in the second domain that adopts a TIM barrel-fold. The third domain, a five-helical bundle, and the C-terminal β-sandwich domain make inter-chain contacts leading to protein dimerization. Informed by the structure of the enzyme in complex with GlcA in its open ring form, in conjunction with mutagenesis studies, the potential substrate binding and catalytically significant amino acids were identified. Based on the catalytic importance of residues located on a highly flexible loop, the enzyme is required to undergo a substantial conformational change to form a productive Michaelis complex with glucuronoxylan.

Expression and Characterization of Glycosyl Hydrolase Family 115 α-Glucuronidase from Scheffersomyces stipitis.

Bajwa, P. K., Harrington, S., Dashtban, M. & Lee, H. (2016). Industrial Biotechnology, 12(2), 98-104. Link to Article Read Abstract The gene encoding glycosyl hydrolase family 115 α-glucuronidase from Scheffersomyces stipitis (ssagu115) was cloned and expressed in Pichia pastoris strain X33. The recombinant enzyme was purified to homogeneity by Ni-chelation affinity chromatography. The apparent molecular weight of the secreted recombinant enzyme was about 150 kDa as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The recombinant α-glucuronidase was able to remove 4-O-methylglucuronic acid groups from several polymeric xylans (beech, birch, and oat spelt xylan) as well as xylooligosaccharides (aldotetraouronic acid and aldopentaouronic acid). The enzyme was more active towards xylooligosaccharides than xylans. Substrate inhibition was observed with aldouronic acids at concentrations above 23 mM. The K_m values of the enzyme towards aldotetraouronic and aldopentaouronic acids were 8.2 mM (5 mg/mL) and 9 mM (6.5 mg/mL), respectively. For beech and birch xylan, the K_m values were 9.5 mg/mL and 35 mg/mL, respectively. The enzyme was active over the pH range of 3.0–8.5, with maximal activity at pH 4.0. The optimum temperature for activity of the enzyme was 50°C. The enzyme exhibited synergy with endoxylanases from the GH10 and GH11 families on hydrolysis of beech xylan, birch xylan, and oat spelt xylan, with the greatest synergistic effect being shown with the GH10 endoxylanase. Treatment of polymeric xylan with SsAgu115 led to reduced solubility and increased precipitation from solution. Insoluble xylans have the potential to form hydrogels, which may have pharmaceutical and biomedical applications.

UV-method for the measurement of α-D-Glucuronidase in various enzyme preparationsPrinciple: (α-D-glucuronidase)(1) Aldouronic acid (NaBH₄ reduced) + H₂O → β-(1,4)-D-xylo-oligosaccharides + D-glucuronic acid (uronate dehydrogenase; UDH)(2) D-Glucuronic acid + NAD⁺+ H₂O → D-glucarate + NADH + H⁺

Kit size: 50 assays (manual) / 200 (microplate)Method: Spectrophotometric at 340 nmReaction time: ~ 25 minDetection limit: 17 mU/mLApplication examples: Enzyme preparations and other materialsMethod recognition: Novel method

Advantages

• Very competitive price (cost per test)
• All reagents stable for > 2 years as supplied
• Simple format
• Mega-Calc™ software tool is available from our website for hassle-free raw data processing
• Standard included
• Suitable for manual, microplate and auto-analyser formats

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