Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Explants of pig small intestine were maintained at 37 degrees C in organ culture for periods up to 24 h in a system using Trowell T-8 medium supplemented with 10% foetal-calf serum. The mucosal morphology was well preserved during culture, as judged by light and electron microscopy. The explant contents of protein and two brush-border enzymes, microvillus aminopeptidase (EC 3.4.11.2) and dipeptidyl peptidase IV (EC 3.4.14.5), were not significantly modified during culture compared with controls, but a moderate, continuous release of both protein and enzyme activities into the medium was observed. Continuous labelling with [35S]methionine resulted in an even incorporation of radioactivity in the protein components, and the rate of labelling only moderately decreased over the 24 h period. The polypeptide compositions of sucrase (EC 3.2.1.48)--isomaltase (EC 3.2.1.10), maltase--glucoamylase (EC 3.2.1.20) lactase (EC 3.2.1.23)--phlorizin hydrolase (EC 3.2.1.62), microvillus aminopeptidase and aspartate aminopeptidase (EC 3.4.11.7) synthesized during culture were studied, and some were found to be similar to those of the pro-forms of the enzymes isolated from animals that had had their pancreatic duct disconnected 3 days before being killed. These results confirmed earlier findings of the existence of pro-forms of some of the microvillar enzymes and thus indicate a low activity of pancreatic proteinases in the culture system.
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PMID:Biosynthesis of intestinal microvillar proteins. Characterization of intestinal explants in organ culture and evidence for the existence of pro-forms of the microvillar enzymes. 709 36

The amounts of lactase (EC 3.2.1.23), sucrase (EC 3.2.1.48), maltase (EC 3.2.1.20), microvillus aminopeptidase (microsomal EC3.4.11.2), and dipeptidyl peptidase IV (EC 3.4.14.X) in biopsies from proximal jejunum and distal ileum were studied by quantitative crossed immunoelectrophoresis and enzymatic assays in obese patients one and six months after jejunoileal bypass operation and compared with peroperative levels. They were related to DNA and protein content. The protein/DNA ratio fell 28-43% postoperatively. Except for ileal lactase and sucrase all enzymes showed decreased levels when expressed per mg protein and an even more pronounced decrease when related to DNA. Lactase and sucrase levels in ileum were increased or unchanged. A constant correlation between the amount of immunoreactive enzyme protein and enzymatic activity was shown for all enzymes except maltase. The results suggest that the bypass operation is followed by an increased amount of enterocytes devoid of or low in enzymatic activity and protein content. The amounts of lactase and sucrase in ileum are increased in relation to the other enzymes. No immunoreactive enzymes with zero or depressed activity were detected.
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PMID:Immunoelectrophoretic studies on human small intestinal brush border proteins: cellular alterations in the levels of brush border enzymes after jejunoileal bypass operation. 742 30

Activities of twelve hydrolytic enzymes in the digestive tract of young rabbits before weaning (4 weeks old) and adult rabbits (3 months old) were measured. The principal digestive enzymes in both groups of rabbits appeared to be amylase (EC 3.2.1.1), maltase (EC 3.2.1.20), pectinase (EC 3.2.1.15) and proteinases. The stomach of young rabbits contained most of the lipolytic activity and 45.7% of the total proteolytic activity of the digestive tract. The highest specific activities (per g digesta) of amylase, maltase and proteinase in young rabbits were found in the small intestine. Total activities (per segment) of amylase and maltase in the small intestine and the caecum were similar. Activities of cellulase (EC 3.2.1.4), inulinase (EC 3.2.1.7) and beta-glucosidase (EC 3.2.1.21) were low and activity of pectinase was fairly high in all segments of the digestive tract. The highest activity of urease (EC 3.5.1.5) was found in the caecum. Enzymic profiles of the colonic chymus resembled those of the caecum. Total hydrolytic activity was lower in the colon than in the caecum. Specific activities of amylase and invertase (EC 3.2.1.26) were lower and those of inulinase and lactase (EC 3.2.1.23) higher in 4-week-old rabbits than in 3-month-old rabbits. Gastric proteinase represented almost half of the total proteolytic activity of the digestive tract, whereas lipolytic activity of gastric contents was not found in measurable quantities in adult rabbits. The caecal contents of adult rabbits contained most of the total activity of lipase (EC 3.1.1.3), cellulase, xylanase (EC 3.2.1.32), pectinase, lactase, invertase, beta-glucosidase and urease present in the digestive tract.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Distribution of activity of hydrolytic enzymes in the digestive tract of rabbits. 753 89

The capacity of intestinal lactase (EC 3.2.1.23) of piglets to hydrolyse lactose in vivo was investigated by measuring the response of blood galactose to doses of lactose, galactose plus glucose and both whole and skimmed milk. Following the administration of oral doses of lactose dissolved in water to piglets from 2 to 18 d of age the adjusted galactose area under the curve (AUC) was between 1.12 and 1.36 arbitrary units, while following a dose of galactose plus glucose dissolved in water it was between 1.56 and 1.98 arbitrary units. Whereas these results suggest that the rate of digestion of lactose appeared to limit the amount of galactose reaching the peripheral blood after a dose of lactose dissolved in water, there was no significant correlation between the capacity of piglets to hydrolyse physiological amounts of lactose and the age of the piglets (2- to 18-d-old piglets; r 0.11). Following oral doses of sow's milk containing either lactose, or galactose plus glucose, the adjusted galactose AUC values were 0.94 and 1.00 arbitrary units respectively, in 10-d-old piglets. Thus, the limitation to the digestion of lactose observed when it was present in water was not evident for lactose in sow's milk. Since there was no significant difference between the adjusted galactose AUC following a dose of whole milk (0.95 arbitrary units) and that following a dose of skimmed milk (1.03 arbitrary units), the presence of fat in sow's milk did not appear to affect the utilization of lactose by the sucking piglets.
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PMID:The responses of blood galactose to oral doses of lactose, galactose plus glucose and milk to piglets. 762 93

Milk lactose is hydrolysed to D-galactose and D-glucose in the small intestine of mammals by the lactase-phlorizin hydrolase complex (LPH, EC 3.2.1.23-62). Lactase activity has broad substrate selectivity and several glycosides are substrates. Recently, using the monodeoxy derivatives of methyl beta-lactoside (1), we have shown the importance of each hydroxyl group in the substrate molecule concerning the interaction with the enzyme. Now we have studied the corresponding O-methyl derivatives, as well as some of the halo derivatives of 1. We have found that the enzyme presents steric restrictions to the recognition of substrates modified in the galactose moiety. In contrast, the binding site for the aglycon part of the substrate is looser. On the other hand, we have previously shown that HO-3' and HO-6 were important for the recognition of the substrate by the enzyme. Now we have found that the corresponding fluorine derivatives are not, or very poorly, recognized. This suggests that the HO-3' and HO-6 participate, as donors, in hydrogen bonds in the interaction with the enzyme.
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PMID:Substrate specificity of small-intestinal lactase: study of the steric effects and hydrogen bonds involved in enzyme-substrate interaction. 764 81

Lactose in yogurt is better absorbed by lactase-deficient subjects than is an equivalent quantity of lactose in milk, presumably because of the microbial activity of the beta-galactosidase present in yogurt. In this study, we describe a process that increases the beta-galactosidase of yogurt 5- to 6-fold and the ability of this high lactase yogurt to enhance lactose absorption in lactase-deficient subjects. These subjects ingested the yogurt meals after a 12-h fast, and lactose malabsorption was determined by measuring breath hydrogen. Breath hydrogen was reduced 39% following ingestion of high lactase yogurt from that after consumption of conventional yogurt, indicating that the high lactase yogurt enhanced lactose absorption. However, the reduction after high lactase yogurt was less than expected, given the 5- to 6-fold increment in beta-galactosidase measured in vitro. In vivo activity of beta-galactosidase requires that the enzyme resist acid denaturation in the stomach. The beta-galactosidase in high lactase yogurt was much less acid resistant than was the beta-galactosidase in conventional yogurt, and the relative inability of high lactase yogurt to enhance lactose absorption was likely due to the destruction of the beta-galactosidase in the stomach.
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PMID:Factors affecting the ability of a high beta-galactosidase yogurt to enhance lactose absorption. 769 33

Seven pyranoses and three furanoses with a nitrogen in the ring were prepared by chemical synthesis, microbial conversion, and isolation from plants to investigate the contribution of epimerization, deoxygenation, and conformation to the potency of inhibition and specificity of mammalian glycosidases. The seven pyranoses are 1-deoxynojirimycin (1), the D-manno (2), D-allo (3), and D-galacto (4) isomers of 1, fagomine (1,2-dideoxynojirimycin, 5), and the D-allo (6) and D-galacto (7) isomers of 5, while the three furanoses are 2,5-dideoxy-2,5-imino-D-mannitol (8), 1,4-dideoxy-1,4-imino-D-arabinitol (9), and 1,4-dideoxy-1,4-imino-D-ribitol (10). The 2-deoxygenation and/or 3-epimerization of 1 enhanced the potency for rat intestinal lactase and bovine liver cytosolic beta-galactosidase. Especially compound 6 showed a potent inhibitory activity against both enzymes, and compound 8, a mimic of beta-D-fructofuranose, was a potent inhibitor of both beta-galactosidases as well. Compound 4, which has been known as a powerful alpha-galactosidase inhibitor, exhibited no significant inhibitory activity for most of mammalian beta-galactosidases. In addition, compound 6 fairly retained a potency of 1 toward rat intestinal isomaltase. In this study, compound 8, known as a processing alpha-glucosidase I inhibitor in cell culture, has been found to have no effect on processing alpha-glucosidase II, whereas 9 has been shown to be a good nonspecific inhibitor of intestinal isomaltase, processing alpha-glucosidase II, Golgi alpha-mannosidases I and II, and porcine kidney trehalase. It has been speculated that glycosidase inhibitors have structures which resemble those of the respective glycosyl cations. This Broad inhibitory activity of 9 toward various glycosidases suggest that it superimposes well on the various glycosyl cations.
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PMID:Nitrogen-in-the-ring pyranoses and furanoses: structural basis of inhibition of mammalian glycosidases. 796 30

The effect of lactose on the urinary excretion of Mg and Ca, as an index of absorption, was studied in a double-blind, crossover study during three 1-week periods. Twenty-four healthy, lactose-tolerant, adult volunteers maintained their habitual diets with the exception that all lactose-containing dairy products in the diet were replaced by 600 g/d of three specially prepared dairy products. These products were based on either lactose-enriched cow's milk or lactose-enriched, lactase (EC 3.2.1.23)-treated cow's milk, with or without added Mg, and were given in turn during 1 week. Lactose intake was increased by 127 mmol/d (46 g/d) while taking the lactose-enriched products. While taking the Mg-enriched products, Mg intake was increased by 2.8 mmol/d (69 mg/d) which was equivalent to 17% of the habitual Mg intake. Apart from the lactose and Mg intake, nutrient intake was comparable during the three dietary periods. Urinary excretions of Mg and Ca were used as indicators for their absorption. Mg supplementation significantly increased urinary Mg excretion by 0.97 mmol/d (equivalent to an increase of 18%, P < 0.001), indicating that urinary Mg excretion is a valid indicator for intestinal Mg absorption. Hydrolysis of lactose did not affect urinary excretion of Mg and Ca, which implies that lactose intake does not affect the absorption of Mg and Ca in healthy adults.
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PMID:Urinary excretion of magnesium and calcium as an index of absorption is not affected by lactose intake in healthy adults. 832 60

To examine the postnatal development of equine small intestine, biopsy specimens of jejunal mucosa from 8 ponies, between 6 and 28 weeks old, were subjected to analytical subcellular fractionation and assay of organelle marker enzymes. Fractionation revealed a reduction in the particulate brush border component of beta-galactosidase (lactase) activity between 6 and 28 weeks, and a corresponding increase in soluble activity, although the reduction in mean specific activity was not significant. There also was a decrease in the proportion of brush border to soluble aminopeptidase N activity, a relative loss of brush border gamma-glutamyltransferase activity, and a considerable decrease in the specific activity of alkaline phosphatase throughout the gradient fractions. In contrast, there were marked increases in activities of alpha-glucosidase (maltase) and sucrase in the older ponies, accompanied by considerable changes in the intracellular distribution of particulate alpha-glucosidase activity, which was predominantly associated with endoplasmic reticulum at 6 weeks, whereas the large increase in activity observed by 28 weeks was clearly associated with the brush border. The modal density of brush borders also increased with age, suggestive of an increase in the glycoprotein-to-lipid ratio of the microvillar membrane. In contrast to these brush border changes, there was relatively little alteration in the activities or density distributions of marker enzymes for endoplasmic reticulum, basolateral membranes, mitochondria, or lysosomes. These findings indicate that maturation of equine intestinal epithelium during the first few months of life results in major changes in the properties and enzyme composition of enterocyte brush borders.
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PMID:Subcellular biochemical changes during the development of the small intestine of pony foals. 853 83

It is known that lactose is better absorbed in yogurts than in milk by lactase-deficient individuals. This fact is due to the presence of beta-galactosidase activity in the yogurts, that are different concerning the caracteristics of the products. Thus, the aim of this study was to verify the absorption and tolerance of lactose in some yogurts consumed by our population. We studied 12 hypolactasic adults who, after diagnostic confirmation, were submitted to three breath hydrogen tests after ingestion of milk and two yogurts with different levels of beta-galactosidase. These activities were determined in each sample utilized. The lactose absorption was evaluated by the measurement of H2 eliminated in the expired air and the tolerance was assessed by the symptoms reported by the participants. The medians of the H2 maximum increment were 20 ppm/min for the milk, 10.5 for yogurt X and 5.5 for the yogurt Y. The area under the curve of H2 concentration presented a median of 960 in the test with milk, 420 with yogurt X and 270 with yogurt Y. These results showed statistically significant differences for milk and the two yogurts and similar among the yogurts. The score for symptoms also were different between the milk and the two yogurts and similar among the yogurts. A statistically significant association between absorption and tolerance was not observed, because many tolerant subjects were malabsorbers of lactose. These data show that lactose in yogurts is better absorbed and better tolerated than lactose in milk, suggesting that our products are similar to those of the literature concerning their capacity of hydrolising lactose "in vivo". In spite of the differences found "in vitro" among the beta-galactosidase, there were no significant differences of absorption and tolerance between the two yogurts studied.
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PMID:[Lactose absorption and tolerance to different types of yogurts in adults with hypolactasia]. 876 81


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