IUBMB Enzyme Nomenclature


Accepted name: cycloisomaltooligosaccharide glucanotransferase

Reaction: cyclizes part of a (1→6)-α-D-glucan chain by formation of a (1→6)-α-D-glucosidic bond

Systematic name: (1→6)-α-D-glucan:(1→6)-α-D-glucan 6-α-D-[1→6α-D-glucano]-transferase (cyclizing)

Comments: Specific for (1→6)-α-D-glucans (dextrans) and, unlike cyclomaltodextrin glucanotransferase (EC, without activity towards (1→4)-α-D-glucans, such as amylose. It also has no activity on oligosaccharides, such as amylopectin and pullulan, containing (1→6)-α-D-glucosidic linkages at branch points. The enzyme from Bacillus circulans T-3040 has been shown to form cycloisomalto-oligosaccharides of three sizes (7, 8 and 9 glucose units). It will also catalyse the disproportionation of two isomalto-oligosaccharides molecules to yield a series of isomalto-oligosachharides and the addition of D-glucose to cycloisomalto-oligosaccharides with ring opening to form isomalto-oligosaccharides.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:


1. Oguma T, Horiuchi, T, and Kobayashi M. Novel Cyclic dextrins, Cycloisomaltooligosaccharides, from Bacillus sp. T-3040 culture. Biosci. Biotech. Biochem. 57 (1993) 1225-1227.

2. Oguma, T., Tobe, K. and Kobayashi, M. Purification and properties of a novel enzyme from Bacillus spp. T-3040, which catalyzes the conversion of dextran to cyclic isomaltooligosaccharides. FEBS Lett. 345 (1994) 135-138. [PMID: 7515357]

3. Yamamoto, T., Terasawa, K., Kim, Y.M., Kimura, A., Kitamura, Y., Kobayashi, M. and Funane, K. Identification of catalytic amino acids of cyclodextran glucanotransferase from Bacillus circulans T-3040. Biosci. Biotechnol. Biochem. 70 (2006) 1947-1953. [PMID: 16926507]

[EC created 2009]

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