Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.108 (lactase)
 2,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Brush borders were prepared from pig intestinal mucosa and the membrane proteins solubilized with either Triton X-100 or papain. Proteins, thus released, were used as antigens to raise antisera in rabbits. The immunoglobulin G fractions were isolated and shown by the double layer immunofluorescence staining technique to react only with the brush border region of the enterocyte. The antibodies obtained were used in immunoelectrophoretic studies on the brush border proteins. Eight hydrolytic activities were identified by the use of histo-chemical staining methods. These were the microsomal aminopeptidase (EC 3.4.11.2), aspartate aminopeptidase (EC 3.4.11.7), dipeptidyl peptidase IV (EC 3.4.14.X), lactase (EC 3.2.1.23), glucoamylase (EC 3.2.1.3), sucrase (EC 3.2.1.48), isomaltase (EC 3.2.1.10) and alkaline phosphatase (EC 3.1.3.1). In addition, at least four faint immunoprecipitates were formed but none of these were identified.
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PMID:Immunoelectrophoretic studies on pig intestinal brush border proteins. 2 Sep 74

A method for measuring brush border membrane enzymes from small intestinal biopsies by crossed immunoelectrophoresis is presented. The use of a brush border specific antiserum made isolation of the brush border membrane before analysis unnecessary. This prevented loss of material which, together with inactivation of enzymes, was a limiting factor in previous studies of brush border enzymes from peroral biopsies. In 58 biopsies from patients without gastrointestinal disorders a close correlation between antigenic activity and corresponding enzymatic activity was shown for the following enzymes: sucrase-isomaltase (EC 3.2.1.48-EC 3.2.1.10), lactase-phlorizin hydrolase (EC 3.2.1.23-EC 3.2.1.62), microvillus aminopeptidase (microsomal, EC 3.4.11.2) and dipeptidyl peptidase IV (EC 3.4.14.X). The immunoelectrophoretic patterns of intestinal mucosa near the ligament of Treitz, and in jejunum and ileum were established. The method presented is thought to be of value in further studies of the molecular basis of brush border diseases.
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PMID:Immunoelectrophoretic studies on human small intestinal brush border proteins. A quantitative study of brush border enzymes from single small intestinal biopsies. 10 36

A brush-border-specific antiserum was raised in rabbits, with Triton X-100-solubilized brush border proteins from pig intestine being used as antigens. The antiserum was used in immunoelectrophoretic studies of brush border proteins solubilized with Triton X-100. Five immunoprecipitates were obtained which corresponded to microsomal aminopeptidase (EC 3.4.11.2), asparate aminopeptidase (EC 3.4.11.7), lactase (beta-galactosidase, EC 3.2.1.23), maltase (exo-1,4-alpha-glucosidase, EC 3.2.1.3) and sucrase-isomaltase (sucrose alpha-glucohydrolase, EC 3.2.1.48). A faint immunoprecipitate was also found for the glycylprolyl dipeptidyl peptidase (EC 3.4.14.-). The brush border proteins were solubilized on a large scale from a brush border membrane preparation by the use of Triton X-100; the peptidases obtained were homogeneous in size and had hydrophobic properties. By chromatography on columns of concanavalin A-Sepharose, hydroxyapatite, Ultrogel AcA 34, DEAE-cellulose and immunosorbent, gamma-glutamyl transpeptidase (gamma-glutamyl transferase, EC 2.3.2.2) and microsomal aminopeptidase were each isolated in separate fractions. Glycylprolyl dipeptidyl peptidase and asparate aminopeptidase were obtained in another fraction. Immunoelectrophoretic, inhibitor and chromatographic studies showed that the intestinal brush border peptidases are similar to the corresponding particulate peptidases obtained from other organs.
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PMID:Intestinal brush border peptidases. 24 83

The human small intestinal brush border proteins were studied qualitatively by crossed immunoelectrophoresis. Brush border membranes were purified from human jejunum and the proteins released by Triton X-100. Rabbits were immunized with the released proteins and by using a double layer immunofluorescence technique the obtained antisera were shown to be specific against the brush border proteins. The precipitates obtained in crossed immunoelectrophoresis were identified by enzymatic staining techniques. Sucrase (EC 3.2.1.48), isomaltase EC 3.2.1.10), maltase (EC 3.2.1.20), phloretin-glucosidase (EC 3.2.1.62), lactase (EC3.2.1.23), microvillus aminopeptidase (aminopeptidase (microsomal), EC 3.4.11.2), dipeptidyl peptidase IV (EC 3.4.14.X), and alkaline phosphatase (EC 3.1.3.1) were identified while asparate aminopeptidase (EC 3.4.11.7), gamma-glutamyl transferase (EC 2.3.2.2) and trehalase (EC 3.2.1.28) could not be visualized. This work demonstrates that cross immunoelectrophoresis can be used in the study of human small intestinal brush border proteins.
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PMID:Immunoelectrophoretic studies on human small intestinal brush border proteins. A qualitative study of the protein composition. 36 59

The brush border of normal small-intestine epithelial cells is rich in enzymes that are involved in the digestive process. Such molecules can be used as markers to analyze cell lineages and differentiation properties of colorectal cancers. Monoclonal antibodies detecting dipeptidyl peptidase-IV, aminopeptidase N, endopeptidase F, sucrase-isomaltase, alkaline phosphatase, maltase-glucoamylase and lactase have been used to analyze the phenotype of colorectal cancers, adjacent mucosa and histologically normal distant mucosa. The avidin-biotin peroxidase complex method was used. Expression of dipeptidyl peptidase-IV, aminopeptidase N, sucrase-isomaltase and alkaline phosphatase was common in non-neoplastic mucosa adjacent to, and distant from, the tumor; in contrast, endopeptidase F, maltase-glucoamylase and lactase were rarely expressed in normal distant mucosa and more frequently expressed in mucosa adjacent to the tumor. Dipeptidyl peptidase-IV, aminopeptidase N, endopeptidase F, sucrase-isomaltase and alkaline phosphatase were frequently expressed in colorectal cancers, whereas maltase-glucoamylase and lactase were rarely expressed. Two general patterns of antibody reactivity were observed: diffuse cytoplasmic and apical; apical reactivity was generally associated with more differentiated tumors. A logistic predictive regression model indicated that enzyme expression in colorectal cancers followed a coordinate pattern, but was unrelated to the location of the tumor, Dukes stage or differentiation grade. In conclusion, expression of brush-border-associated enzymes occurs frequently in colorectal cancers and is regulated in a co-ordinated manner. These markers can be used for the phenotypic sub-classification of colorectal cancers.
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PMID:Intestinal brush-border-associated enzymes: co-ordinated expression in colorectal cancer. 134 6

Suckling rats were given urogastrone-epidermal growth factor (EGF: 1,000 micrograms/kg body weight) or vehicle by gavage at one of three stages of development: 8 to 10, 11 to 13 or 14 to 16 days of age. Intubation was carried out at 8-hourly intervals over these periods. Fourteen to 16 h after the last intubation the rats were killed; that is, at 11, 14 and 17 days respectively. Samples of proximal and distal small intestine (SI) were taken for enzyme analysis. Five enzymes were assayed; sucrase, lactase, gamma-glutamyl transferase, alkaline phosphatase and neutral amino-peptidase, and their activities expressed per g protein. Treatment with EGF had no effect on body weight or on the length of the small intestine at any age. The nature of the effects on enzyme activities depended on the specific enzyme concerned, the site within the small intestine and the timing of the treatment. Lactase was increased by EGF at both sites only on day 14, whereas gamma-glutamyl transferase was increased in proximal samples at 11 and 14 days, and in distal samples at 17 days. Nor was the outcome always to increase activity. On day 11 alkaline phosphatase was increased in proximal SI, but decreased in distal SI; and so too was aminopeptidase N decreased in distal SI at 11 days. Sucrase showed no response at all. The pattern is complex. Certainly it does not indicate accelerated functional maturation.
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PMID:Effects of urogastrone-epidermal growth factor and age at administration on five enzymes in the small intestine of suckling rats. 136 15

Expression and cellular localization of brush-border enzymes (aminopeptidase N, dipeptidylpeptidase IV, lactase, maltase) in normal human colon, colonic polyps and malignant intestinal tumors were investigated with a panel of monoclonal antibodies reacting with either native or denatured proteins. The enzymes were detected on cryostat sections by indirect immunofluorescence staining, or affinity-purified and analyzed by gel electrophoresis and immunoblotting. Dipeptidylpeptidase IV, lactase and maltase were absent from all samples examined, while aminopeptidase N (APN) was detected at the basal membrane of the epithelial cells in most specimens of colon obtained from individuals free of intestinal tumors. In contrast, APN was frequently localized at the luminal membrane of the surface epithelium in large-intestinal mucosa distal to tumors, adenomas and hyperplastic polyps, and from members of hereditary colon cancer syndrome families. APN was also expressed in colonic tumors, where it was present in an apical cell membrane location in 3/23 adenomas and 14/35 adenocarcinomas examined. No correlation was found between tumor-cell invasiveness (classified by "Dukes" stage) and expression or cellular location of aminopeptidase N. Histologically, all positive tumors were moderately or well differentiated. These results suggest that aminopeptidase N is normally expressed in adult human colon, but epithelial cells in the large and small intestine differ in their ways of sorting this enzyme intracellularly and eventually inserting it into different aspects of their surface membrane, a process which may be altered at an early stage of carcinogenesis.
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PMID:Expression and different polarity of aminopeptidase N in normal human colonic mucosa and colonic tumors. 137 88

Growth failure is a major complication of chronic hypoxemia, as seen in infants and children with cyanotic congenital heart disease. To determine whether chronic hypoxemia during infancy affects the gastrointestinal tract, we examined small intestinal growth and digestive enzyme activities in chronically hypoxemic newborn lambs and in age-matched controls. Chronic hypoxemia was produced by placing an inflatable occluder around the main pulmonary artery and performing a balloon atrial septostomy. Aortic oxygen saturation was reduced to 60-74% for 2 wk, after which the small intestine was removed for analysis. During chronic hypoxemia, somatic growth rate was decreased to 60% of control (hypoxemic, 135 +/- 20 versus control, 216 +/- 26 g/d, p less than 0.02). No differences in caloric intake were found (hypoxemic, 129 +/- 4 versus control, 128 +/- 4 kcal/kg/d). Chronic hypoxemia did not alter small intestinal growth, as measured by jejuno-ileal weight, jejuno-ileal length, mucosal weight, or mucosal protein or DNA contents. However, sp act of lactase, the principal disaccharidase of the infant lamb intestine, were significantly decreased (hypoxemic, 0.08 +/- 0.01 versus control, 0.146 +/- 0.03 units of enzyme activity/mg DNA, p less than 0.05), as were the total small intestinal contents of lactase (hypoxemic, 61.7 +/- 7.0 versus control, 120.6 +/- 21.7 units of enzyme activity, p less than 0.01). There also were decreases in specific and total activities of other digestive enzymes such as maltase, amino-oligopeptidase, and alkaline phosphatase in hypoxemic intestine that did not achieve statistical significance.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Alterations in postnatal intestinal function during chronic hypoxemia. 156 Oct 8

Ten groups of calves were used to study the changes in activity levels and distribution of seven hydrolases in the intestinal mucosa during development and weaning. The calves in the first group were sacrificed at birth while those in the remaining nine groups were either milk-fed until slaughter on days 2, 7, 28, 56, 70, and 119; or weaned between days 28 and 56 and then slaughtered on days 56, 70, and 119, respectively. The small intestine was immediately cut off and divided into five segments, ie, duodenum, proximal jejunum, median jejunum, distal jejunum, and ileum. In the milk-fed animals, the activity levels of aminopeptidases A and N, alkaline phosphatase, lactase, and isomaltase were maximum at 2 days of age, and then declined sharply between days 2 and 7 but did not change significantly thereafter. By contrast, the maltase activity increased between days 7 and 119, while no sucrase activity was detected. Weaning resulted in a decrease in the activity of lactase and an increase in that of aminopeptidase N, maltase, and isomaltase. The distribution of all these enzymes along the small intestine was slightly influenced by age but not at all by weaning.
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PMID:Activity distribution of seven digestive enzymes along small intestine in calves during development and weaning. 172 29

To investigate the biosynthetic basis for the mosaic expression of brush border enzymes in confluent Caco-2 cells, a human colon carcinoma cell line exhibiting characteristics of adult small intestinal enterocytes, we have obtained a series of clones differing markedly in their growth rates, amounts of transforming growth factor-alpha/epidermal growth factor-like activity released into the culture medium, and sucrase-isomaltase (SI) activity. Other intestinal markers (aminopeptidase N, dipeptidylpeptidase IV, lactase, alkaline phosphatase and 'crypt cell antigen') displayed a much more limited variability in expression, suggesting that the Caco-2 cell clones we have obtained did not differ in their overall ability to differentiate. Immunofluorescence staining, metabolic labelling with radioactive methionine and hybridization analysis of SI mRNA abundance were used to investigate SI synthesis and its regulation in clones endowed with low, intermediate or high sucrase activity. The results obtained have demonstrated heterogeneous SI expression, even in clonal cell lines, and a negative correlation between SI expression and growth factor concentrations in the culture medium, suggesting an autocrine regulation of cell proliferation and differentiation in confluent Caco-2 cells. Pulse-chase experiments using the two clones endowed with the lowest and highest levels of SI activity, followed by immunoprecipitation of labelled SI with epitope-specific antibodies and SDS/PAGE analysis, suggested that both transcriptional and post-translational mechanisms play a role in the regulation of SI expression in intestinal cells.
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PMID:Clonal analysis of sucrase-isomaltase expression in the human colon adenocarcinoma Caco-2 cells. 176 23


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