Glucuronyl esterases (GE) constitute a recently discovered class of enzymes, first reported in 2006. These enzymes are involved in delignification, hydrolysing the ester linkages between lignin polyphenol structures and the glucuronoxylan present in the hemicellulose fraction of lignocellulosic biomass. Given that these linkages are believed to contribute to the recalcitrant nature of lignocellulose, the discovery of new and improved glucuronyl es-terases is an important target for the biofuel industry. A number of synthetic substrates to measure GE activity have previously been described in the literature. Building on these seminal studies, we prepared a range of substrates which, when combined with two ancillary enzymes, namely a GH67 α-glucuronidase from Geobacillus stearothermophilus and a GH43 β-xylosidase from Selenomonas ruminantium, form the basis of a colourimetric assay kit (K-GEUX3) for glucuronyl esterases.
