A-Glucosidase maltase

The a-amylase analyzer of Fuji Electric (Japan) (Osawa et al., 1981) is based on a GOD electrode (see Table 23). The sensor measures the endogenous glucose concentration of the sample and the rate of glucose liberation after addition of maltopentaose and a-glucosidase (maltase). 

The uptake of maltose and maltotriose is mediated by specific inducible permeases [20, 21], A coordinated induction of an a-glucosidase (maltase) also occurs, so that on entering the cell both sugars are hydrolyzed to glucose [22,23]. Neither the permeases nor the maltase are synthesized in the presence of glucose (>0 4% w/v for brewing yeasts [24]) and hence are said to be catabolite repressed [25]. 

Yeasts are also a good source of an a-glucosidase. However, yeast a-glucosidase (maltase) as ordinarily prepared loses its activity very rapidly. 

The end product of the degradation of polysaccharides by amylases is maltose (and isomaltose) glucose arises to a minor extent by the cleavage of maltotriose into two fragments. In the intestinal tract, an a-glucosidase (= maltase) splits maltose to glucose and thus ends the digestion. Maltase can also split sucrose. 

Data obtained by other workers through different experimental approaches also point to the same conclusion. Weidenhagen11 demonstrated that at its optimum pH 7, maltase (a-glucosidase), which had... 

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-... 

Although dilute aqueous acid hydrolyzed the methyl and benzyl a-D-fructofuranosides approximately 8 and 16 times as rapidly as sucrose, their method of preparation showed them to be unaffected by any of the enzymes active in a fermenting yeast suspension. Purified yeast invertase, proven free of a-D-glucosidases (maltases), could therefore contain no enzyme capable of hydrolyzing the above two a-D-fructo-furanosides, but did contain constituents that readily cleaved the beta isomers and also sucrose. The latter is accordingly a /S-D-fructofuranos-ide. When the evidence is put in this way, the present uncertainties as to whether purified invertase preparations include one or a number of /3-D-fructofuranosidases, and whether or not sucrose, methyl and... 

Miglitol (Glyset) is another a-glucosidase inhibitor, but in contrast to acarbose, mightol is systemically absorbed prior to its activity in the small intestine. It also appears to inhibit the enzymes sucrase and maltase to a greater extent than does acarbose. It does not undergo metabolism and is renally excreted unchanged. 

The reduced glycemic index has been attributed to PPT-mediated inhibition of a-amyl-ase, maltase, or a-glucosidase (sucrase)," " but the inhibition of these enzymes is not relevant when volunteers have been given glucose per These observations are... 

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