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)

In vitro studies of lactose hydrolysis in milk with 20-125 neutral lactase units (NLUs) carried out at 38.0 degrees C for 15 min with a beta-galactosidase derived from Kluyveromyces lactis (Lactaid, Lactaid Inc, Pleasantville, NJ) resulted in 85-95% of the hydrolysis observed with standard incubation conditions (24 h at 4-5 degrees C with 1000 NLU/L). Thirty-three lactose-maldigesting Guatemalan subjects, 16 children and 17 adults, were challenged with oral doses of lactose in milk (children aged less than 12 mo, 2 g/kg body wt; children aged 12-24 mo, 15 g/kg body wt; older children and adults, 18 g/kg body wt) preincubated for 20 min at 38 +/- 0.5 degrees C with 50-125 NLU Lactaid. Under these conditions the subjects consumed milk without presenting any signs of intolerance. Furthermore, their breath-hydrogen excretion showed a 91-93% reduction when compared with a similar load of milk containing nonhydrolyzed lactose.
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PMID:Effect of temperature on the lactose hydrolytic capacity of a lactase derived from Kluyveromyces lactis. 210 55

The regulatory mechanism of decline in catalytic activity for intestinal lactase (lactase-phlorizin hydrolase, beta-galactosidase) as mammals mature has not been defined. Solubilized intestinal brush-border membranes from adult male rats (greater than 4 months of age, 200-400 g) were examined by high performance liquid Zorbax GF-450 chromatography, subjected to denaturing acrylamide electrophoresis, blotted to nitrocellulose, and identified by specific polyvalent anti-lactase. Three major species were present within the 235-kDa active lactase peak (225, 130, and 100 kDa). The 100-kDa moiety was also prominent in the approximately 300-kDa region of the GF-450 effluent, suggesting it is a catalytically inactive oligomer. In vivo synthesis and assembly of lactase by intraintestinal pulse [( 35S]methionine, 5 min) and chase (15-120 min) revealed rapid (15 min of chase; maximum, 60 min) intracellular synthesis in the endoplasmic reticulum-Golgi fraction of multiple species (64, 100, 130, 175, and 225 kDa). The 64-kDa species disappeared from the intracellular membrane compartment and was not transferred to the brush-border surface. The 175-kDa moiety appeared to be processed to the 225-kDa unit prior to relocation to the surface membrane. By 120 min, the 100-kDa species became the predominant (approximately 60%) radiolabeled unit in both endoplasmic reticulum-Golgi and brush border. In the adult rat, lactase is assembled in multiple molecular forms that are differentially processed: (a) intracellular degradation (64-kDa unit) or (b) transfer to the brush-border surface as catalytically active (225 and 130 kDa) or inactive (100 kDa) species. Although substantial synthesis of lactase proteins prevails, major changes in processing appear to serve as an important regulatory mechanism producing the maturational decline of catalytic activity. The accompanying article (Castillo, R. O., Reisenauer, A. M., Kwong, L. K., Tsuboi, K. K., Quan, R., and Gray, G. M. (1990) J. Biol. Chem. 265, 15889-15893) extends our studies to synthesis and assembly during the neonatal period of maturation.
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PMID:Intestinal lactase. Shift in intracellular processing to altered, inactive species in the adult rat. 211 32

The aim of the present experiment was to determine the influence of either probiotic or antibiotic inclusion in the diets of pigs from birth on the development of enzyme activity in the small intestine. Pigs were fed on creep feed and grower diets containing either a probiotic, an antibiotic or no added growth promoter. At 7, 17, 42 and 80 d of age pigs from each treatment group were sampled to investigate the development of carbohydrase and peptidase activity in the mucosa at five sites along the small intestine. Inclusion of either the probiotic or antibiotic had a significant effect on the development of sucrase (sucrose alpha-D-glucohydrolase; EC 3.2.1.48), lactase (beta-D-galactoside galactohydrolase; EC 3.2.1.23) and tripeptidase (EC 3.4.11.4) activities before weaning but had no effect on depeptidase (EC 3.14.13.11) activity. The study of the distribution of enzyme activity along the small intestine showed significant differences between the proximal and distal sections associated with weaning.
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PMID:The influence of inclusion of either an antibiotic or a probiotic in the diet on the development of digestive enzyme activity in the pig. 211 23

Lactase deficient subjects, who form the bulk of the world population, absorb yogurt lactose because the bacteria used for fermentation produce beta-galactosidase. From a milk fermented by these bacteria and dried by a temperature-controlled process a power could be obtained which possess residual lactase activity but, unlike yogurt, does not need storage at low temperature. The lactose of this fermented powdered milk is perfectly absorbed, as proved by hydrogen respiratory tests performed in 35 lactose intolerant African subjects living in isolated villages. In 25 malnourished children under 3 years of age, this milk allowed renutrition without inducing diarrhoea--a result which could not have been obtained with ordinary milk in two-thirds of the cases. This type of food is potentially valuable to feed the large population of the third world.
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PMID:[Use of a fermented powdered milk in malnourished or lactose intolerant children]. 213 60

Adult rats that were maintained on a low-carbohydrate intake showed rapid increase in the activities of sucrase, maltase, and lactase along the length of the small intestine when they were fed a high-starch diet. In the present study, we have identified these activity increases, and showed that they reflect proportional accumulations in enzyme-protein of sucrase-isomaltase (EC 3.2.1.10, 3.2.1.48), maltase-glucoamylase (EC 3.2.1.20), and neutral lactase (EC 3.2.1.23). It was determined that each of these enzymes exists in adult rat intestine in single immunoreactive form and accounts as a group for all sucrase, cellobiase, and most maltase and lactase activities. Dietary change from low to high carbohydrate (starch) resulted in an increase in [3H]leucine accumulation in each of the enzymes, without a change in the amount of label accumulation in total intestinal proteins. The increase in label accumulation in the brush-border carbohydrase pools was matched generally by proportional elevation in the pool concentrations of sucrase-isomaltase and lactase but not maltase. These studies suggest that the elevation of intestinal carbohydrase concentrations induced by high-carbohydrate feeding may involve selective stimulation of their synthesis.
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PMID:Nature of elevated rat intestinal carbohydrase activities after high-carbohydrate diet feeding. 241 70

We report the primary structures of human and rabbit brush border membrane beta-glycosidase complexes (pre-pro-lactase-phlorizin hydrolase, or pre-pro-LPH, EC 3.2.1.23-62), as deduced from cDNA sequences. The human and rabbit primary translation products contain 1927 and 1926 amino acids respectively. Based on the data, as well as on peptide sequences and further biochemical data, we conclude that the proteins comprise five domains: (i) a cleaved signal sequence of 19 amino acids; (ii) a large 'pro' portion of 847 amino acids (rabbit), none of which appears in mature, membrane-bound LPH; (iii) the mature LPH, which contains both the lactase and phlorizin hydrolase activities in a single polypeptide chain; (iv) a membrane-spanning hydrophobic segment near the carboxy terminus, which serves as membrane anchor; and (v) a short hydrophilic segment at the carboxy terminus, which must be cytosolic (i.e. the protein has an Nout-Cin orientation). The genes have a 4-fold internal homology, suggesting that they evolved by two cycles of partial gene duplication. This repetition also implies that parts of the 'pro' portion are very similar to parts of mature LPH, and hence that the 'pro' portion may be a water-soluble beta-glycosidase with another cellular location than LPH. Our results have implications for the decline of LPH after weaning and for human adult-type alactasia, and for the evolutionary history of LPH.
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PMID:Complete primary structure of human and rabbit lactase-phlorizin hydrolase: implications for biosynthesis, membrane anchoring and evolution of the enzyme. 246 Mar 43

Adult rats when fed a high carbohydrate diet of 70% sucrose or glucose for 24 h following a 4-day fast showed increased concentrations of intestinal sucrase-isomaltase (EC 3.2.1.48, EC 3.2.1.10) and maltase-glucoamylase (EC 3.2.1.20) but not lactase-phlorizin hydrolase (EC 3.2.1.23, EC 3.2.1.62). The concentration increases of these enzymes were accompanied by corresponding acceleration of their synthesis rates. Contrary to earlier studies by others, suggesting that upper villus cells in the fasted intestine are unresponsive to stimulation of sucrase activity by refeeding a high-sucrose diet, the concentration increases of both sucrase-isomaltase and maltase-glucoamylase were seen to occur in cells all along the length of the villus column. The earlier studies differed from the present study by basing enzyme assays relative to protein rather than the DNA content of villus cell fractions. We have shown that villus cells increase their protein content severalfold while migrating to villus tip, providing the basis for the difference between earlier and the present findings. Further evidence that stimulation of sucrase-isomaltase and maltase-glucoamylase by high carbohydrate is not restricted to the crypt and lower villus region was obtained by the finding that their synthesis rates appeared to be equally stimulated along the length of the villus column.
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PMID:Dietary CHO and stimulation of carbohydrases along villus column of fasted rat jejunum. 249 55

Lactase-deficient subjects absorb lactose in yogurt more effectively than lactose in other dairy products. However, as all previous studies were performed without a double-blind design and only after a single ingestion of the test product, the mechanism of this enhanced absorption remains unclear. The aims of this double-blind study were 1) to evaluate lactose absorption after prolonged ingestion of yogurt and fermented-then-pasteurized milk (FPM) and 2) to assess the modification of the lactase activity of the duodenal mucosa. In 16 lactase-deficient subjects we confirmed that yogurt enhances lactose digestion, this beneficial effect being destroyed by pasteurization. Moreover, the long-term (8 d) ingestion of either yogurt or FPM does not modify the results of hydrogen breath tests in comparison with a 24-h ingestion. The mucosal lactase (Dahlquist method) and beta-galactosidase (ONPG method) activities were not significantly modified by yogurt or FPM ingestion. These results suggest that in lactase-deficient subjects no adaptation occurs after eating yogurt or FPM and that the increased lactose absorption in yogurt must be mainly related to an intraluminal process.
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PMID:Yogurt and fermented-then-pasteurized milk: effects of short-term and long-term ingestion on lactose absorption and mucosal lactase activity in lactase-deficient subjects. 249 32

1. Intestinal structure, lactase (beta-galactosidase; EC 3.2.1.23) activity and alkaline phosphatase activity have been determined in mouse jejunal and ileal tissues before and during infection with the intestinal parasite Nematospiroides dubius. 2. Oral infection with small numbers of N. dubius larvae caused villus height, crypt depth and enterocyte migration rate to increase in the mouse jejunum. None of these effects occurred in ileal tissue. 3. Lactase activity also increased in jejunal, but not ileal, tissue of infected mice. This increase was associated with a doubling of the rate at which activity appeared in the brush-border membrane of enterocytes during migration over the basal regions of jejunal villi. Alkaline phosphatase activity in jejunal tissue remained unchanged in infected mice. 4. Attention is drawn to the fact that this is the first occasion when crypt cell hyperplasia has been found to be positively correlated with an increase in lactase activity and a decrease in cytotoxic/suppressor T-cells. Further work is needed to establish the primary cause of these effects.
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PMID:Intestinal infection with Nematospiroides dubius selectively increases lactase expression by mouse jejunal enterocytes. 250 31

The enzyme beta-galactosidase was first mentioned in the literature by Beijerinck exactly a hundred years ago. The Department of Microbiology and Enzymology of the Delft University of Technology keeps the memory of Beijerinck, its first professor, alive by maintaining a 'Beijerinck-room' in the attic of the building. In addition to manuscripts and laboratory notebooks, this room contains some of his chemicals and biological preparations, and it was here that we recently found a 90-year old lactase preparation. Even after storage under suboptimal conditions, the preparation still exhibited measurable enzyme activities.
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PMID:The discovery of beta-galactosidase. 251 Mar 75


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