Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The acceptor products of maltose with Leuconostoc mesenteroides B-512FM dextransucrase are panose (6(2)-alpha-D-glucopyranosyl maltose) and a homologous series of 6(2)-isomaltodextrinosyl maltoses. The structures of the acceptor products of dextransucrase with other maltodextrins, maltotriose to maltooctaose (G3-G8), were determined by using the known specificities of alpha-glucosidase and porcine pancreatic alpha-amylase, and by methylation analysis. It has been found that dextransucrase transfers a D-glucopyranosyl residue to C-6 of either the nonreducing end or the reducing end residues of the maltodextrins, G3-G8, forming an alpha(1----6) linkage. When a D-glucose was transferred to the nonreducing residue, the first product was also an acceptor to give the second product, which served as an acceptor to give the third product, etc. to give a homologous series. When D-glucose was transferred to the reducing residue, the first product did not readily serve as an acceptor to give products or it served only as a very poor acceptor to give a small amount of the next homologue. The effectiveness of maltodextrins as acceptors decreased as the size of the maltodextrin chain increased. Maltotriose was 40% as effective as maltose and maltooctaose was only 6% as effective.
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PMID:Acceptor reactions of maltodextrins with Leuconostoc mesenteroides B-512FM dextransucrase. 214 65

Three pseudo-aminosugars, validamine, valienamine and valiolamine, produced by Streptomyces hygroscopicus subsp. limoneus showed potent inhibitory action on rat small intestinal carbohydrase activities such as sucrase, maltase, glucoamylase, isomaltase and trehalase activities, but negligible action on lactase activity and pancreatic alpha-amylase activity. Where inhibition was seen, kinetic analysis showed fully competitive inhibition of the carbohydrase activities by all three inhibitors. Valiolamine has more potent carbohydrase inhibitory activity than validamine or valienamine, and the apparent Ki values of valiolamine for sucrase, maltase, glucoamylase, isomaltase and trehalase activities were 3.2 x 10(-7), 2.9 x 10(-6), 1.2 x 10(-6), 9.1 x 10(-7) and 4.9 x 10(-5) M, respectively, which are 10(-5) to 10(-3) times smaller than the apparent Km values.
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PMID:Inhibitory effect of validamine, valienamine and valiolamine on activities of carbohydrases in rat small intestinal brush border membranes. 226 98

Incubation of zymosan particles with serum was shown to be accompanied by their partial breakdown into the oligosaccharides maltose, maltotriose, and maltotetraose, that were quantified under the form of glucose after degradation by alpha-glucosidase. Incubation with normal adult serum yielded twice as much glucose than incubation with cord serum. The degradation of zymosan could be mimicked by incubation with purified pancreatic alpha-amylase. A correlation was also found between the amount of oligosaccharides released from the particles during their incubation with serum and the concentration of amylase in the sera. The latter is low in newborns and increases several-fold, to nearly adult levels, at 3-6 months of age. Preincubation of zymosan with purified pancreatic alpha-amylase resulted in an approximately 50% increase in the binding of radioactive anti-C3c in the supernates obtained after subsequent incubation with cord serum but not with adult serum. With six of 24 cord sera, but not with adult serum, it also resulted in an augmentation of the chemiluminescence accompanying the phagocytosis of the particles after their opsonization. It is concluded that the relative inefficiency of cord and newborn serum in opsonizing zymosan is attributable not only to their lower content of the components of the alternative pathway of complement, but also to a lower concentration of serum amylase.
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PMID:Effect of age-dependent enzymatic degradation of zymosan into oligosaccharides during incubation with serum on its opsonization by complement. 241 86

Purified E. histolytica amylases III to VI were characterized by their hydrolytic behaviour towards 4-nitrophenyl alpha-malto-oligosaccharides, malto-oligosaccharides, amylose, amylopectin, glycogen and Y-cyclodextrin. The influence of specific inhibitors on the amylase activity of E. histolytica was examined and compared with typical alpha- and beta-amylases. Amylases III and IV showed alpha-glucosidase and glucosyltransferase activity by cleaving terminal non-reducing glucose from pNPG1 (III, IV) and pNPG2 to pNPG7 (III). Both enzymes were able to cleave malto-oligosaccharides and glucopolysaccharides to a large number of malto-oligosaccharides. Also transglucosidation reactions were observed, but maltose was not hydrolysed. Amylase V showed exoamylase-like properties by preferentially cleaving maltose units from the non-reducing end of synthetic and biogenic malto-oligosaccharides by a multiple-attack mechanism. Amylase VI was characterized as an alpha-amylase, showing great similarities with porcine pancreatic alpha-amylase in the hydrolysis pattern of 4-nitrophenyl alpha-malto-oligosaccharides and glucopolysaccharides. With biogenic malto-oligosaccharides amylase VI showed a transglucosidation reaction.
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PMID:Separation and characterization of four different amylases of Entamoeba histolytica. II. Characterization of amylases. 242 98

Dietary fibres (Plantago ovata seeds, P. ovata husks, wheat bran, alfalfa, pectin, xylan) were incubated in vitro with gastrointestinal enzymes (pepsin, trypsin, chymotrypsin, lipase, alpha-amylase, maltase, lactase) in buffer solutions at concentrations of 1-5% for 10-30 min at 37 degrees C. All fibres induced sometimes pronounced changes in enzyme activity, but the effect of the different fibres on the various enzymes varied individually and was not predictable. Both P. ovata preparations had no (pepsin, trypsin, alpha-amylase) or only stimulating (chymotrypsin, lipase, lactase) actions whereas all other fibres showed inhibiting as well as stimulating influences. Wheat bran induced the most pronounced alterations increasing lipase, maltase and lactase activity and inhibiting alpha-amylase activity. Pectin and xylan were comparable in decreasing lipase and pepsin activity and in increasing chymotrypsin activity but had opposite effects on maltase activity. Alfalfa was able to stimulate lactase and lipase activity but depressed trypsin and alpha-amylase activity. The inactivation of enzymes by dietary fibres can, at least partly, be explained by adsorption to the fibre or by the presence of enzyme inhibitors especially in natural compounds. The reasons for activation processes are unknown. As enzyme activities are decisive for food digestion, the properties of the individual fibres should be carefully considered when used as dietary supplement in physiological or pathological conditions.
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PMID:Interference of dietary fibres with gastrointestinal enzymes in vitro. 248 92

Starch-degrading, amylolytic enzymes are widely distributed among microbes. Several activities are required to hydrolyze starch to its glucose units. These enzymes include alpha-amylase, beta-amylase, glucoamylase, alpha-glucosidase, pullulan-degrading enzymes, exoacting enzymes yielding alpha-type endproducts, and cyclodextrin glycosyltransferase. Properties of these enzymes vary and are somewhat linked to the environmental circumstances of the producing organisms. Features of the enzymes, their action patterns, physicochemical properties, occurrence, genetics, and results obtained from cloning of the genes are described. Among all the amylolytic enzymes, the genetics of alpha-amylase in Bacillus subtilis are best known. Alpha-Amylase production in B. subtilis is regulated by several genetic elements, many of which have synergistic effects. Genes encoding enzymes from all the amylolytic enzyme groups dealt with here have been cloned, and the sequences have been found to contain some highly conserved regions thought to be essential for their action and/or structure. Glucoamylase appears usually in several forms, which seem to be the results of a variety of mechanisms, including heterogeneous glycosylation, limited proteolysis, multiple modes of mRNA splicing, and the presence of several structural genes.
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PMID:Microbial amylolytic enzymes. 254 11

Starch is the main carbohydrate in the food of poultry. Starch granules are digested by pancreatic alpha-amylase in the small intestine. Intestinal villi have enterocytes that project microvilli with a fibrous glycocalyx from the surface. These fine structures are envisaged to entrap water that is mixed with mucin from nearby goblet cells to form the "unstirred water layer." Maltose, maltotriose and alpha-limit dextrins must diffuse across this first barrier to absorption to be hydrolyzed by maltase and sucrase-isomaltase immobilized at the membrane; however, the resultant glucose, once formed, accrues at the surface to provide a concentration advantage. Fowl adjust to changes in dietary starch by altering the amount of amylase released, intestinal surface area and enterocyte carbohydrase concentration. Enterocytes arising during embryonic development have no carbohydrases and are not involved with glucose absorption, but they appear to be specialized for maternal immunoglobin transfer in ovo. Embryonic villi are stimulated by transfer activity, and their growth depends on enterocytes arising from the crypt. Mature crypt cells are capable of digestion-absorptive activities and dominate the villus shortly after the chick hatches when yolk sac reserves are depleted.
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PMID:Digestion and absorption of carbohydrates in fowl and events through perinatal development. 258 3

By means of biochemical determination of the activity of hydrolases in the digestive system, studies have been made on the enzymic spectrum in the pancreas and small intestine in postnatal life of astrakhan sheep. It was shown that to the moment of birth, animals possess the developed mechanisms of the initial and final stages of hydrolysis of proteins and lipids. At this period, carbohydrate hydrolysis system is presented only by lactase, the activity of pancreatic alpha-amylase, intestinal gamma-amylase and maltase being very low, whereas the activity of saccharides is absent at all. During further development of sheep, the activity of all digestive hydrolases gradually increases, except that of lactase which is almost absent in adult specimens. Saccharides activity was not find in the mucose of the small intestine within the whole postnatal life.
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PMID:[The enzyme systems of the cavitary and membrane hydrolysis of foodstuffs in the ontogeny of Karakul sheep]. 259 5

The determination of alpha-amylase activity using an ethylidene-blocked 4-nitrophenyl-maltoheptaoside (EPS) has been evaluated in five laboratories on eight different analysers at 25 degrees C, 30 degrees C and 37 degrees C. The protecting ethylidene group inhibits hydrolysis at the non-reducing end of the substrate molecule by the auxiliary enzyme, alpha-glucosidase. The combined reagent is therefore stable for at least 10 days at 2-8 degrees C. HEPES is used, because the molar absorbance of 4-nitrophenol is independent of temperature in the presence of this buffer. Compared with the method using unprotected substrate 4-nitrophenyl-alpha-D-maltoheptaoside (4NP-G7), the present method is equal or better with respect to the imprecision, linearity and interlaboratory transferability of results in human and control sera. Since the protected and unprotected substrates differ in their turnover rate, the new assay yields activities which differ from those of the 4-nitrophenyl-alpha-D-maltoheptaoside method. Based on the homogeneous results obtained in method comparisons between EPS and 4-nitrophenyl-alpha-D-maltoheptaoside, and in order to maintain the 4-nitrophenyl-alpha-D-maltoheptaoside reference values, a conversion factor was derived to eliminate the above differences: activityEPS x 2.50 = activity4NP-G7. The temperature and instrument independence of this relationship was demonstrated in a total of 720 human sera and plasmas.
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PMID:Evaluation of a new alpha-amylase assay using 4.6-ethylidene-(G7)-1-4-nitrophenyl-(G1)-alpha-D-maltoheptaoside as substrate. 278 87

The effect of eight doses of 10,000, 20,000 and 30,000 UI of vitamin D2 administered every other day to three groups of rats, on the activities of some enzymes in the animals' liver was evaluated. In general terms, findings revealed a decrease in the activities of glucose-6-phosphatase, phosphorylase and arginase. Likewise, an increase of the activities of maltase and of glutamic oxaloacetic and glutamic pyruvic transaminases was observed. Furthermore, the activities of cholinesterase and alpha-amylase also varied depending on the vitamin D2 doses administered.
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PMID:[Effect of hypervitaminosis D on the activity of various enzymes in the rat liver]. 282 Mar 34


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