Carbohydrate-active enzyme discovery is often not accompanied by experimental validation, demonstrating the need for techniques to analyze substrate specificities of carbohydrate-active enzymes in an efficient manner. DNA sequencer-aided fluorophore-assisted carbohydrate electrophoresis (DSA-FACE) is utmost appropriate for the analysis of glycoside hydrolases that have complex substrate specificities. DSA-FACE is demonstrated here to be a highly convenient method for the precise identification of the specificity of different -L-arabinofuranosidases for (arabino)xylo-oligosaccharides ((A)XOS). The method was validated with two -L-arabinofuranosidases (EC 22.214.171.124) with well-known specificity, specifically a GH62 -L-arabinofuranosidase from Aspergillus nidulans (AnAbf62A-m2,3) and a GH43 -L-arabinofuranosidase from Bifidobacterium adolescentis (BaAXH-d3). Subsequently, application of DSA-FACE revealed the AXOS specificity of two -L-arabinofuranosidases with previously unknown AXOS specificities. PaAbf62A, a GH62 -L-arabinofuranosidase from Podospora anserina strain S mat+, was shown to target the O-2 and the O-3 arabinofuranosyl monomers as side chain from mono-substituted -D-xylosyl residues, whereas a GH43 -L-arabinofuranosidase from a metagenomic sample (AGphAbf43) only removes an arabinofuranosyl monomer from the smallest AXOS tested. DSA-FACE excels ionic chromatography in terms of detection limit for (A)XOS (picomolar sensitivity), hands-on and analysis time, and the analysis of the degree of polymerization and binding site of the arabinofuranosyl substituent.
- Substrate specificity
- Enzyme analysis
- INDUCED FLUORESCENCE DETECTION
- (1,4)-BETA-D-ARABINOXYLAN ARABINOFURANOHYDROLASE