Reaction: Hydrolysis of (1→6)-α-D-glucosidic linkages in some oligosaccharides produced from starch and glycogen by EC 22.214.171.124 (α-amylase), and in isomaltose
Other name(s): limit dextrinase (erroneous); isomaltase; sucrase-isomaltase; exo-oligo-1,6-glucosidase; dextrin 6α-glucanohydrolase; α-limit dextrinase; dextrin 6-glucanohydrolase; oligosaccharide α-1,6-glucohydrolase; α-methylglucosidase
Systematic name: oligosaccharide α-1,6-glucohydrolase
Comments: This enzyme, like EC 126.96.36.199 (amylo-α-1,6-glucosidase), can release an α-1→6-linked glucose, whereas the shortest chain that can be released by EC 188.8.131.52 (pullulanase), EC 184.108.40.206 (limit dextrinase), and EC 220.127.116.11 (isoamylase) is maltose. It also hydrolyses isomaltulose (palatinose), isomaltotriose and panose, but has no action on glycogen or phosphorylase limit dextrin. The enzyme from intestinal mucosa is a single polypeptide chain that also catalyses the reaction of EC 18.104.22.168 (sucrose α-glucosidase). Differs from EC 22.214.171.124 (amylo-α-1,6-glucosidase) in its preference for short-chain substrates and in its not requiring the 6-glucosylated residue to be at a branch point, i.e. linked at both C-1 and C-4.
Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9032-15-9
1. Hauri, H.-P., Quaroni, A. and Isselbacher, K.J. Biogenesis of intestinal plasma membrane: posttranslational route and cleavage of sucrase-isomaltase. Proc. Natl. Acad. Sci. USA 76 (1979) 5183-5186. [PMID: 291933]
2. Sjöström, H., Norén, O., Christiansen, L., Wacker, H. and Semenza, G. A fully active, two-active-site, single-chain sucrase-isomaltase from pig small intestine. Implications for the biosynthesis of a mammalian integral stalked membrane protein. J. Biol. Chem. 255 (1980) 11332-11338. [PMID: 7002920]
3. Rodriguez, I.R., Taravel, F.R. and Whelan, W.J. Characterization and function of pig intestinal sucrase-isomaltase and its separate subunits. Eur J Biochem. 143 (1984) 575-582. [PMID: 6479163]