Arabinanases

Arabinanases are enzymes that catalyze the hydrolysis of arabinan, a plant cell wall polysaccharide composed mainly of L-arabinofuranose units linked by α-1,5-glycosidic bonds, with branching from α-1,3 and α-1,2 links. They belong to families of glycoside hydrolases and can act on arabinan in various plant materials, yielding arabino-oligosaccharides or arabinose.

There are endo-acting arabinanases that cleave internal α-1,5 linkages in the arabinan backbone, producing shorter chains, and exo-acting enzymes that remove arabinose residues from the ends of chains. Some arabinanases also debranch side chains containing arabinose. Substrate specificity varies among enzymes from different organisms.

Arabinanases are produced by a range of microorganisms, including fungi such as Aspergillus and Trichoderma species and bacteria such as Bacillus and Clostridium. Many enzymes are secreted into the extracellular medium to aid degradation of plant material, and activity is influenced by pH and temperature, with sources ranging from mesophilic to thermophilic.

Industrial applications include degradation of arabinan-rich plant biomass for biofuel and biochemical production, modification of pectin-containing foods and beverages, prebiotic arabino-oligosaccharide production, and improving digestibility in animal feeds. Ongoing research targets improved activity, stability, and altered substrate preferences through protein engineering and discovery in diverse microbial genomes.

See also: arabinan, arabinofuranosidase, glycoside hydrolase.