ExplorEnz: EC 3.2.1.196

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3.2.1.196

Accepted name:

limit dextrin α-1,6-maltotetraose-hydrolase

Reaction:

Hydrolysis of (1→6)-α-D-glucosidic linkages to branches with degrees of polymerization of three or four glucose residues in limit dextrin.

Other name(s):

glgX (gene name); glycogen debranching enzyme (ambiguous)

Systematic name:

glycogen phosphorylase-limit dextrin maltotetraose-hydrolase

Comments:

This bacterial enzyme catalyses a reaction similar to EC 3.2.1.33, amylo-α-1,6-glucosidase (one of the activities of the eukaryotic glycogen debranching enzyme). However, while EC 3.2.1.33 removes single glucose residues linked by 1,6-α-linkage, and thus requires the additional activity of 4-α-glucanotransferase (EC 2.4.1.25) to act on limit dextrins formed by glycogen phosphorylase (EC 2.4.1.1), this enzyme removes maltotriose and maltotetraose chains that are attached by 1,6-α-linkage to the limit dextrin main chain, generating a debranched limit dextrin without a need for another enzyme.

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc, PDB

References:

1.	Jeanningros, R., Creuzet-Sigal, N., Frixon, C. and Cattaneo, J. Purification and properties of a debranching enzyme from Escherichia coli. Biochim. Biophys. Acta 438 (1976) 186–199. [DOI] [PMID: 779849]
2.	Dauvillee, D., Kinderf, I.S., Li, Z., Kosar-Hashemi, B., Samuel, M.S., Rampling, L., Ball, S. and Morell, M.K. Role of the Escherichia coli glgX gene in glycogen metabolism. J. Bacteriol. 187 (2005) 1465–1473. [DOI] [PMID: 15687211]
3.	Song, H.N., Jung, T.Y., Park, J.T., Park, B.C., Myung, P.K., Boos, W., Woo, E.J. and Park, K.H. Structural rationale for the short branched substrate specificity of the glycogen debranching enzyme GlgX. Proteins 78 (2010) 1847–1855. [DOI] [PMID: 20187119]

[EC 3.2.1.196 created 2016]