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)

At various postnatal stages, intestinal epithelial cells were isolated sequentially from villus tip to crypt base by successive EDTA treatments. According to the localization of marker enzymic activities, isolated cells were pooled into three cell compartments: villus (V), lower villus and upper crypt (VC) and crypt (C). Purified brush-border-membrane proteins were separated by 7.5%-polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. Enzymic activities could be assigned to some protein bands: maltase/glucoamylase (protein band 3), sucrase-isomaltase (protein bands 3 and 6), lactase (protein band 5) and alkaline phosphatase (region of protein bands 8 and 9). The findings suggest the following. (1) Sucrase-isomaltase activities appeared in compartment C at 17 days with a simultaneous increase of the pre-existing protein band 3 and appearance of a well-defined protein band in position 6; the enzymic complex remained still present in the crypt cells until adulthood. From the day 21 onwards, sucrase-isomaltase was detected in compartments VC and V. (2) Lactase was only present in the three cell compartments until day 21; at this developmental stage its activity completely disappeared from compartment C, in spite of the persistence of a weak protein band. (3) Alkaline phosphatase activity could be detected as a single peak corresponding to protein band 9 in all three cell compartments until day 21; thereafter it was replaced by two peaks of activity showing a less precise correlation with the well-defined protein bands 8 and 9. In the crypt cells of the adult rat, however, the preweaning situation, which was regularly observed, is an unexpected phenomenon. (4) Maltase and glucoamylase did not display any marked qualitative or quantitative modifications either along the villus-crypt axis or during the period of postnatal development studied. Evidence is given from the present data that each brush-border enzyme investigated has a specific developmental pattern.
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PMID:Developmental pattern of rat intestinal brush-border enzymic proteins along the villus--crypt axis. 10 86

Lactase and maltase, the predominant sugar hydrolases associated with the intestinal brush bordermembrane of the suckling rat, were purified essentially free of the other to near homogeneity (lactase at specific activity 23, maltase at specific activity 58), and their specific physiocochemical properties determined. Antisera prepared to each showed by immunodiffusion a single common precipitin line with pure enzyme and solubilized proteins of the brush border membrane. Brush border membranes were purified 26--35-fold from infant rat intestine. Membranes prepared from 10-day-old rats contained 32% protein, 43% lipid and 25% carbohydrate with lactase and maltase estimated to comprise in excess of 10% and 2%, respectively, of the membrane protein. Immunotitration curves of lactase and maltase showed equivalent antibody binding by the membrane-bound and free enzyme forms. Furthermore, antibody binding to one enzyme did not affect the immunotitration curve or the extractability (by papain or Triton X-100) of the other membrane-bound enzyme. It was concluded that the lactase and maltase molecules are attached singly on the external membrane surface in a spatially independent manner with their antigenic sites as freely available to antibody binding as exhibited by their papain-solubilized counterparts.
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PMID:Sugar hydrolases of the infant rat intestine and their arrangement of the brush border membrane. 11 Mar 47

72 h after ligation or external fistulation of the common duct the activities of maltase, sucrase and lactase in the homogenate of the small intestinal mucosa of the rat were determined. The experiments were performed in connexion with intestinal perfusion studies, and the disaccharidase activities were measured in unperfused intestinal segments as well as in intestinal loops which had previously been perfused with a sucrose-containing solution. After bile duct ligation, the sucrase and maltase activities in a previously perfused intestinal loop were not different from those in sham-operated animals, the lactase activity was diminished. In a nonperfused segment, the sucrase activity was greater, the maltase activity was unchanged, and the lactase activity was lower than in control animals. After bile duct fistulation, the sucrase, maltase and lactase activities in a perfused segment were lower than in sham-operated rats. In a nonperfused loop, the sucrase activity was greater, the maltase activity was unchanged, and the lactase activity was lower then in the corresponding control group. These data suggest that bile is a factor which influences the total mucosal disaccharidase activities, and, probably, the intracellular enzyme distribution.
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PMID:Ligation or external fistulation of the common bile duct in the rat. II. Intestinal disaccharidase activities. 11 Jun 39

This study was undertaken to investigate the effect of alcohol on the activity of jejunal disaccharidases (DS). The activity of DS in a preparation of purified brush border membrane of hamster jejunum was measured in the absence and in the presence (0.8 to 6.4% wt/vol) of ethanol. To compare the effect of alcohol on DS with its action on a brush border enzyme of a different group, we also measured the activity of alkaline phosphatase (AP) under similar conditions. Ethanol depressed the activity of sucrase, maltase, and lactase in a dose-dependent and time-dependent manner, but it stimulated the activity of AP. The ethanol-induced inhibition of DS was completely reversible. Kinetic studies indicate that ethanol depressed the Vmax and increased the Km of sucrase and lactase. The Vmax of maltase also decreased, but the Km of this hydrolase was not affected by ethanol. From the results of this study it would appear that acute exposure of the jejunal brush border to ethanol depresses the DS activity of the membrane and that (because the AP was not depressed) the ethanol-induced inhibition of DS is not the result of a general inhibition of all enzymes of the brush border.
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PMID:Effect of ethanol on disaccharidases of hamster jejunal brush border membrane. 11 61

The effect of undernutrition on rat small intestine during the critical newborn period was studied. A severe state of protein-energy malnutrition was induced by litter expansion which caused the mean total body weight of experimentally malnourished rats to diminish significantly as compared to control animals. Intestinal weight and total DNA were similarly diminished in the malnourished rats. DNA and protein expressed per gram wet tissue showed no significant differences between groups. Retarded intestinal growth in the malnourished animals was the result of reduced cell number. The mean specific activities of sucrase and maltase were diminished in the experimental group, with mean activities being 20 to 50% of controls, respectively. These differences were larger when expressed as total organ activities. On the other hand, specific lactase activity was significantly higher in undernourished rats but total lactase activity per organ was similar in both groups. Enterokinase specific activity or total organ activity was significantly higher in the undernourished rats.
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PMID:The effect of early postnatal acquired malnutrition on intestinal growth, disaccharidases and enterokinase. 11 73

The arrangement of the sugar hydrolases, sucrase-isomaltase, maltase, and lactase on the microvillus membrane of rat intestine was investigated by immunological technique. The enzymes were purified essentially free of each other to near homogeneity and antisera of high specificity were obtained against each. Microvillus membranes were prepared routinely in high purity from rat intestine and contained an average 61% protein, 20% lipid, and 19% carbohydrate, with the sugar hydrolases comprising an estimated 20--25% of the membrane protein. The immunoreactivity of membrane-bound sucrase-isomaltase, maltase, and lactase was investigated with antisera demostrating specific reactivity to each, when tested in the presence of other membrane extractives. The membrane-bound enzymes were found in each case to combine with antibody in amounts equivalent to that required to effect precipitation of comparable units of the free enzymes from solution. Preloading membrane vesicles with antibodies to any two of the enzymes did not affect either the immunoreactivity or extractability (by papain or Triton X-100) of the third. The antibody-binding studies indicated an arrangement of these enzymes independent of each other on the membrane surface, in a manner allowing each to maintain a high degree of molecular freedom.
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PMID:Sugar hydrolases and their arrangement on the rat intestinal microvillus membrane. 11 6

Intestinal lactase activity (with its associated cellobiase, 4-methylumbelliferyl-beta-galactosidase and -beta-glucosidase activities) was used as a specific intestinal marker enzyme to study the release of protein and enzymes of intestinal origin in sheep amniotic fluid during gestation. In amniotic fluid, intestinal lactase activity peaked at 66--85 days of gestation and then decreased with gestation. This enzyme activity was very low or absent in allantoic fluid throughout gestation suggesting that there is no important transfer of amniotic fluid lactase towards the allantoic cavity. Maltase and 4-methylumbelliferyl-alpha-glucosidase showed no statistically significant variation with gestation in both amniotic and allantoic fluid whereas alpha-galactosidase and N-acetyl-beta-hexosaminidase which were first higher in allantoic than in amniotic fluid increased in amniotic fluid to reach allantoic fluid levels near term. Such patterns are consistent with the suggestion that the fetal urine is a source of alpha-galactosidase and N-acety-beta-hexosaminidase activities and that sheep urine is first accumulated in the allantoic sac via the urachus up to 86--90 days of gestation and thereafter passes more and more into the amniotic sac.
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PMID:Origin and developmental patterns of lactase and other glycosidases in sheep amniotic and allantoic fluid. 11 4

The effects of deoxycholate, taurocholate and cholate on transport and mucosal ATPase activity have been investigated in the rat jejunum in vivo using closed-loop and perfusion techniques. In the closed-loops, 5 mM deoxycholate selectively inactivated (Na+ + K+)-ATPase, and net secretion of Na+ induced by 2.5 mM deoxycholate was due to reduced lumen to plasma flux of the ion; deoxycholate (2.5 mM) produced marked inhibition of 3-0-methylglucose transport. Luminal disappearance rates of deoxycholate (60.5 plus or minus 2.9% per g wet st of gut) greatly exceeded those of taurocholate (4.3 plus or minus 1.0). In the perfusion studies 1 mM deoxycholate induced net secretion of water, Na+ and C1-, and inhibited active glucose transport; concomitantly "total" ATPase, (Na+ + K+)-ATPase, and Mg-2+-ATPase were inhibited. At higher concentrations (5 mM) deoxycholate stimulated Mg-2+-ATPase activity. Taurocholate and cholate at 1mM had no effect on transport of (Na+ + K+)-ATPase. Mucosal lactase, sucrase and maltase activities were not affected by 1 mM deoxycholate, taurocholate or cholate. These results suggest that deoxycholate inhibits sodium-coupled glucose transport by inhibition of (Na+ + K+)-ATPase at the lateral and basal membranes of the epithelial cell, rather than from an effect at the brush-border membrane level.
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PMID:A comparative study on the effects of different bile salts on mucosal ATPase and transport in the rat jejunum in vivo. 12 87

Mucosal response of alkaline phosphatase, ATPase and disaccharidase (lactase, maltase and trehalase) activities to sex hormones were studied by comparing male and female rats and castrated males and by injecting testosterone into castrated males. Alkaline phosphatase showed a very steep gradient in the small intestine from the oral to the aboral end, whereas ATPase activity in the ileum was still about 50% of that in the duodenum. Both enzymes showed only minor sex variations and weal response to castration. Lactase and maltase had peak activities in the jejunum, but trehalase activity was nearly equally high in the duodenal mucosa as in the jejunum. Jejunal lactase activity was about 50% lower in female than in male rats and castration decreased activity in males to the same low level as found in females. The administration of testosterone to castrated male rats did not enhance activity. Maltase activity showed similar sex variation, although castration was not able to decrease activity during the test period. Trehalase activity was lower in female than in male rats. The administration of testosterone enhance activity in castrated males.
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PMID:Sex variation in the activities of mucosal hydrolytic enzymes in the small intestine of the rat. 12 35

Specific and total activities of lactase, sucrase and maltase were determined in the mucosa scraped from the proximal, mid and distal intestinal segments of nonpregnant and pregnant normal control and diabetic rats. In control rats, pregnancy was accompanied by a significant rise in total lactase activity of the entire intestinal mucosa. This was due to increased specific activity of the enzyme in the mid segment of the pregnant rats. In both nonpregnant and pregnant rats, diabetes was associated with marked enhancement of intestinal growth and with elevated specific and total activities of the three mucosal disaccharidases. In the pregnant diabetic rats, specific and total activities of the disaccharidases were about 30% lower than corresponding values in the nonpregnant diabetic rats.
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PMID:Intestinal disaccharidases in the rat: effects of pregnancy and diabetes. 13 Apr 71


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