Dextrinase, limit

This enzyme [EC 3.2.1.10] (also referred to as oUgo-1,6-glucosidase, sucrase-isomaltase, and limit dextrinase) catalyzes the hydrolysis of l,6-o -D-glucosidic linkages in isomaltose and dextrin products generated from starch and glycogen via a-amylase. See also Sucrase... 

The latest International Union Biochemicals report includes an enzyme 3.2.1.41 a-dextrin endo-l,6-a-glucosidase, other names limit dextrinase, amylopectin 6-glucanohydrolase, pullulanase. 

Dohlert and Knutson (1991) and D. J. Manners (personal communication) reported that extracts of sugary maize contain a mixture of limit dextrinase and isoamylase. However, James et al. (1995) reported that su 1 codes for the isoamylase. 

The plant and bacterial enzymes capable of hydrolyzing pullulan do not have identical specificities. In particular, the plant enzymes have little or no action on glycogen and phytoglycogen under conditions in which they readily hydrolyze amylopectin and its /3-dextrin. To stress this difference (the bacterial enzymes are capable of degrading both glycogen and phytoglycogen), Manners (1997) recommended different nomenclature for bacterial enzymes, to be called pullulanase, and the plant enzymes, to be called limit dextrinases. 

The limit-dextrinase activity of malted barley is important in distilhng and brewing, since its activity controls the conversion of starch into fermentable sugars. ... 

Broad-bean limit-dextrinase, originally termed R-enzyme, has been used for the structural analysis of a-dextrins for example, 6 -a-maltosylmalto-triose [0-a-n-glucopyranosyl-(l—>4)-0-a-D-glucopyranosyl-(l- 6)-0-a-n-... 

Alpha-dextrin endo-1,6-alpha-glucosidase. Pullulanase. Pullulan 6-glucanohydrolase. Limit dextrinase. Debranching enzyme. 3.2.1.41 Starch-debranching enzyme, hydrolyses (l-6)-alpha-glucosidic linkages in pullulan and starch to form maltotriose. 

Furegon, L., Peruffo, A.D.B., and Curioni, A., Immobilization of rice limit dextrinase on Y-alumina beads and its possible use in starch processing, Proc. Biochem., 32, 113, 1997. 

The levels of limit dextrinase in germinating rye have been monitored. ... 

A carbohydrase-free limit dextrinase from malted sorghum flour readily... 

The results of a detailed comparison of the relative efficiencies of different procedures for solubilizing the membrane-bound a-o-glucosidases of porcine intestinal mucosa have been reported. Procedures for the selective solubilization of certain members of the complex group of a-D-glucosidases have b en developed. The selective solubilization led to the conclusion that separate a-D-glucosidases (isomaltase and limit dextrinase respectively) are involved in the hydrolysis of isomaltose and the a-limit dextrins formed from starch by a-amylase. 

GA induces de novo synthesis of proteinase, limit dextrinase, pentosanases and a-glucosidase Undisputed... 

GA—these are limit dextrinase and a-glucosidase [47]. The significance of these enzymes in the hydrolysis of starch reserves is discussed in Chapter 6. jS-Amylase is not synthesized de novo in the presence or absence of GA, but is carried over in an inactive form from the developing grain. It may be activated indirectly by GA through induction of a proteinase which releases it from its inactive bound form (Chap. 6). 

Gibberellic acid induced the de novo synthesis of limit dextrinase in barley grains with excised embryos. ... 

A limit dextrinase isolated from broad-bean ( Vicia fabd) flour readily hydrolysed branched a-dextrins containing maltosyl or maltotriosyl side-chains, pullulan, and amylopectin j6-limit dextrin, whereas it hydrolysed glycogen -limit dextrin and amylopectin slowly and glycogens not at all. ... 

The substrate specificities of purified limit dextrinases from ungerminated oats (Avena sativa) and rice Oryza sativd) have been compared with that of a bacterial isoamylase/ The cereal enzymes are able to hydrolyse a-(l 6)-D-glucosidic linkages in oligosaccharides, a-dextrins, pullulan, amylopectin, and the -limit dextrins of amylopectin and glycogen, but are unable to hydrolyse glycogens. 

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