Isomaltase

A case similar to the slow, practically irreversible inhibition of jack bean a-D-mannosidase by swainsonine is represented by the interaction of castanospermine with isomaltase and rat-intestinal sucrase. Whereas the association constants for the formation of the enzyme-inhibitor complex were similar to those of other slow-binding glycosidase inhibitors (6.5 10 and 0.3 10 M s for sucrase and isomaltase, respectively), the dissociation constant of the enzyme-inhibitor complex was extremely low (3.6 10 s for sucrase) or could not be measured at all (isomaltase), resulting in a virtually irreversible inhibition. Danzin and Ehrhard discussed the strong binding of castanospermine in terms of the similarity of the protonated inhibitor to a D-glucosyl oxocarbenium ion transition-state, but were unable to give an explanation for the extremely slow dissociation of the enzyme-inhibitor complex. 

The principle of active-site-directed inactivation of glycosidases by gly-con-related epoxides can be extended to compounds having an exocyclic oxirane ring, either directly attached to the six-membered ring (32) or at some distance (33,34). Studies with -o-glucosidase from sweet almonds and intestinal sucrase-isomaltase revealed that, in spite of the higher intrinsic reactivity of these epoxides, this shift of the position of the epoxide function causes a 10- to 30-fold decrease of kj(max)/Ki, an effect which probably reflects the limited flexibility of the catalytic groups involved in the epoxide reaction. 

V al-Met-Ser-Asp-T rp-Ala-Ala-His-His-Ala-Gly-Val-)S-D-Glucosidase A (bitter almonds) lle-Thr-Glx-Glx-Val-Phe-Gly-Asp-Ser-(Ala, Asxj, Glx, Pro)-Lys ff-D-Glucosidase (human placenta, lysosomal) -Val-Ala-Ser-Gln-Lys-Asn-Asp-Leu-Asp-Ala-Val-Ala-a-D-Glucosidase (sucrase, rabbit small intestine) -lle-Asp-Met-Asn-Glu-Pro-Asn-a-D-Glucosidase (isomaltase, rabbit small intestine) -Gly-Gly-Gln-lle-Asp-Met-)ff-D-Galactosidase (Escherichia co//) -Ser-Leu-Gly-Asn-Glu-Ser-Gly-His-Gly-Ala-... 

Low-density lipoprotein (LDL) receptor Human lymphocyte antigen CD8 Interleukin-2 receptor Rat renal a-glutamyltranspeptidase Sucrase and isomaltase... 

A novel 13-membered ring thiocyclitol (214), isolated from Salacia reticulata Wight (family Hippocrateaceae), showed promising a-glucosidase inhibitory activity (IC50 maltase, 0.227 /tM sucrase, 0.186 //M isomaltase, 0.099 however, it did not inhibit a-amylase from porcine pan-... 

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... 

Oligo-( 1— 6)-D-glucosidase isomaltase, dextrin 6-a-D-glucanohydrolase hydrolysis of (1— -6)-a-D-glucosyl links in isomaltose, panose, and gluco-oligosaccharides produced from starch by alpha amylase... 

Isomaltase-sucrase deficiency This enzyme deficiency results in an intolerance of ingested sucrose. This disorder is found in about ten percent of Greenland s Eskimos, whereas two percent of North Americans are heterozygous for the deficiency. Treatment is to withhold dietary sucrose. 

Biochemical part of the barrier contains alkaline phosphatase, y-glutamytranspeptidase, dipeptidylpep-tidase IV, aminopeptidase N, endopeptidase 24-11 and disaccharidases saccharidase, isomaltase, lactase. Among metabolising enzymes Phase I enzymes CYP 1A1 and 3A4 and Phase II enzymes glutathion-S-transferase, sulfotransferase and glucuronidase are present. 

Zweibaum A, Traidou N, Kedinger M et al. (1983) Sucrase-isomaltase a marker of foetal and malignant epithelial cells of the human colon. Int J Cancer 32 407 112 Zweibaum A, Pinto M, Chevalier G et al. (1985) Enterocytic differentiation of a subpopulation of the human colon tumor cell line HT-29 selected for growth in sugar-free medium and its inhibition by glucose. J Cell Physiol 122 21-29... 

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