Glycoside hydrolase family 51 α-L-arabinofuranosidases from Clostridium thermocellum and Cellvibrio japonicus release O-5-feruloylated arabinose

Arabinofuranosidases act synergistically with other enzymes to depolymerize arabinoxylans by cleaving arabinofuranose substituents from the β-(1→4)-linked D-xylopyranose backbone. Because arabinose feruloylation is a barrier to some, but not all, arabinofuranosidases, we investigated the actions of three α-L-arabinofuranosidases from the glycoside hydrolase (GH) family 51 on feruloylated arabinoxylan-oligosaccharide standard compounds with and without feruloyl esterase. GH51 α-L-arabinofuranosidases from Clostridium thermocellum and Cellvibrio japonicus both partially released feruloylated arabinose (up to 59% for C. thermocellum). Simultaneous incubation with arabinofuranosidases and feruloyl esterase quantitatively released arabinose from feruloylated standard compounds. Therefore, although feruloylation does not completely obstruct GH51 arabinofuranosidases, synergistic approaches utilizing multiple enzymes remain the most effective tactic for enzymatic breakdown of feruloylated compounds.