Reaction: Hydrolysis of chitosan or chitosan oligosaccharides to remove successive D-glucosamine residues from the non-reducing termini
Glossary: GlcN = D-glucosamine = 2-amino-2-deoxy-D-glucopyranose
GlcNAc = N-acetyl-D-glucosamine
Other name(s): CsxA; GlcNase; exochitosanase; GlmA; exo-β-D-glucosaminidase
Systematic name: chitosan exo-1,4-β-D-glucosaminidase
Comments: Chitosan is a partially or totally N-deacetylated chitin derivative that is found in the cell walls of some phytopathogenic fungi and comprises D-glucosamine residues with a variable content of GlcNAc residues [4]. Acts specifically on chitooligosaccharides and chitosan, having maximal activity on chitotetraose, chitopentaose and their corresponding alcohols [1]. The enzyme can degrade GlcN-GlcNAc but not GlcNAc-GlcNAc [3]. A member of the glycoside hydrolase family 2 (GH-2) [4].
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:
References:
1. Nanjo, F., Katsumi, R. and Sakai, K. Purification and characterization of an exo-β-D-glucosaminidase, a novel type of enzyme, from Nocardia orientalis. J. Biol. Chem. 265 (1990) 10088-10094. [PMID: 2351651]
2. Nogawa, M., Takahashi, H., Kashiwagi, A., Ohshima, K., Okada, H. and Morikawa, Y. Purification and characterization of exo-β-D-glucosaminidase from a cellulolytic fungus, Trichoderma reesei PC-3-7. Appl. Environ. Microbiol. 64 (1998) 890-895. [PMID: 16349528]
3. Fukamizo, T., Fleury, A., Côté, N., Mitsutomi, M. and Brzezinski, R. Exo-β-D-glucosaminidase from Amycolatopsis orientalis: catalytic residues, sugar recognition specificity, kinetics, and synergism. Glycobiology 16 (2006) 1064-1072. [PMID: 16877749]
4. Côté, N., Fleury, A., Dumont-Blanchette, E., Fukamizo, T., Mitsutomi, M. and Brzezinski, R. Two exo-β-D-glucosaminidases/exochitosanases from actinomycetes define a new subfamily within family 2 of glycoside hydrolases. Biochem. J. 394:675 (2006). [PMID: 16316314]
5. Ike, M., Isami, K., Tanabe, Y., Nogawa, M., Ogasawara, W., Okada, H. and Morikawa, Y. Cloning and heterologous expression of the exo-β-D-glucosaminidase-encoding gene (gls93) from a filamentous fungus, Trichoderma reesei PC-3-7. Appl. Microbiol. Biotechnol. 72 (2006) 687-695. [PMID: 16636831]