Acetylxylan esterase (AXE)

Acetylxylan esterase (AXE) is a microbial enzyme that plays a vital role in the degradation of plant biomass by removing acetyl groups from the xylan backbone of hemicellulose. This deacetylation reduces steric hindrance, facilitating the action of xylanases and other glycoside hydrolases in breaking down the cell wall into fermentable sugars [1, 4]. AXEs are classified into several Carbohydrate Esterase (CE) families (such as CE1-CE7 and CE16) based on their amino acid sequences and structural folds, often utilizing a canonical Ser-His-Asp catalytic triad [2, 12, 15]. While not currently a target for human therapeutic drugs, AXE is of high industrial significance in the production of biofuels, paper pulp, and animal feed, as well as in the food industry for modifying the texture of polysaccharides [3, 13, 16]. In the human body, AXE activity is provided by the gut microbiota, which utilizes these enzymes to metabolize dietary fibers that are otherwise indigestible by human enzymes [15]. Additionally, some AXE variants from the CE7 family possess cephalosporin-C deacetylase activity, making them useful biotechnological tools for the synthesis of precursors for semi-synthetic cephalosporin antibiotics [13, 17].

Other names

Xylan acetyl-esteraseAcetylesteraseHemicellulose deacetylaseCarbohydrate esterase

Acetylxylan esterase catalyzes the hydrolytic deacetylation of xylans and xylo-oligosaccharides by cleaving the ester linkages of acetyl groups at the O-2 and/or O-3 positions of xylose residues in the hemicellulose backbone.