Reaction: Hydrolysis of α-L-Araf-(1→3)-D-Galp bonds in side chains of the non-reducing termini of type II arabinogalactan attached to proteins.
Glossary: Araf = arabinofuranose
Arap = arabinopyranose
Galp = galactopyranose
Other name(s): 3-O-α-D-galactosyl-α-L-arabinofuranosidase; β-arabino-oligosaccharide 3-O-β-L-arabinopyranosyl-α-L-arabinofuranoside; type II arabinogalactan exo α-(1,3)-[α-D-galactosyl-(1→3)-L-arabinofuranose] hydrolase (non-reducing end); arabinogalactan exo α-(1,3)-α-D-galactosyl-(1→3)-L-arabinofuranosidase (non-reducing end)
Systematic name: type II arabinogalactan α-(1,3)-[α-L-arabinofuranosyl-(1→3)-D-galactopyranoside] hydrolase
Comments: The enzyme hydrolyses L-Araf-(1→3)-D-Galp bonds in different side chains of the non-reducing termini of arabinogalactan polysaccharides. The enzyme from the bacterium Bifidobacterium longum is particularly active with gum arabic arabinogalactan, a type II arabinogalactan produced by acacia trees. It acts on α-D-Galp-(1→3)-α-L-Araf-(1→3)-D-Galp side chains, releasing α-D-Galp-(1→3)-L-Araf disaccharides [1], and can also act (with much lower activity) on β-L-Arap-(1→3)-L-Araf-(1→3)-D-Galp side chains, releasing β-L-Arap-(1→3)-L-Araf disaccharides. The enzyme from Bifidobacterium catenulatum has wider specificity and can release longer oligosaccharides with the formula (β-L-Araf-(1→2)-)n-β-L-Arap-(1→3)-α-L-Araf (n = 0-3) [2].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Sasaki, Y., Horigome, A., Odamaki, T., Xiao, J.Z., Ishiwata, A., Ito, Y., Kitahara, K. and Fujita, K. Novel 3-O-α-D-galactosyl-α-L-arabinofuranosidase for the assimilation of gum arabic arabinogalactan protein in Bifidobacterium longum subsp. longum. Appl. Environ. Microbiol. 87 (2021) e02690-20. [PMID: 33674431]
2. Sasaki, Y., Matsuo, A., Hashiguchi, M., Fujimura, K., Koshino, H., Tanaka, K., Ito, Y., Kitahara, K., Ishiwata, A. and Fujita, K. Structural analysis of gum arabic side chains from Acacia seyal released by bifidobacterial β-arabino-oligosaccharide 3-O-β-L-arabinopyranosyl-α-L-arabinofuranosidase. Carbohydr. Polym. 349 (2025) 122965. [PMID: 39643419]