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

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

Acute uremia was induced in rats with temporary clamping of the left renal pedicle and contralateral nephrectomy. Jejunal peptidase activities (aminopeptidase N, dipeptidyl peptidase IV and aminopeptidase A), disaccharidase activities (maltase, sucrase, lactase and trehalase) and morphology were studied. A significant (p less than 0.05) increase in aminopeptidase N activity and a positive correlation between aminopeptidase N activity and serum urea was found in the uremic rats. The other peptidase activities showed a slight increase in the uremic rats. A shortening of the microvilli of the small intestinal epithelial cells in the uremic rats was seen by electron microscopy. The disaccharidase activities was unaltered. This study shows the presence of functional alterations in the small intestine in rats with acute uremia. The observations are also compatible with different regulation mechanisms for the brush border peptidases and disaccharidases.
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PMID:Small intestinal peptidases and disaccharidases in rats with acute uremia. 192 11

The adult guinea-pig small intestinal microvillus membrane was purified approximately 25-fold by both cation-precipitation and differential centrifugation methods. Comparison by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed no substantial differences in polypeptide composition between the two preparations. One-dimensional SDS-PAGE and two-dimensional isoelectric focussing (IEF)/SDS-PAGE, together with Coomassie-blue, silver and lectin-staining, showed three major high molecular weight polypeptides, Mr 108 000, 116 000 and 127 000, as well as a 47 kDa protein (actin), as major constituents of the membrane. The proteins of Mr 108 000 and 116 000 were strongly concanavalin A reactive. A detailed two-dimensional IEF/SDS-PAGE map of the membrane was constructed. Sodium carbonate treatment showed the two concanavalin A-reactive glycoproteins, Mr 108 000 and 116 000, comprising the sucrase-isomaltase complex, to be loosely-associated 'extrinsic' microvillus membrane proteins. Two proteins, Mr 127 000 and 135 000, were tightly-associated 'intrinsic' microvillus proteins. Despite regional differences in specific activity of some small intestinal microvillar enzymes, most noticeably enterokinase (EC 3.4.21.9) and dipeptidyl peptidase IV (EC 3.4.14.x), no substantial regional differences were seen in microvillus membrane polypeptide composition. In contrast, a substantial increase in the major high molecular weight proteins of Mr 108 000 and 116 000 accompanied a 10-fold rise in sucrase-isomaltase activity, and loss of a major protein of Mr 131 000 accompanied the complete loss of lactase activity from the membrane during postnatal development.
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PMID:Two-dimensional isoelectric focussing/sodium dodecyl sulphate polyacrylamide gel electrophoretic mapping and some molecular characteristics of the proteins of the adult guinea-pig small intestinal microvillus membrane. 399 21

The activities of brush border membrane-associated hydrolases such as alkaline phosphatase (Alkpase), aminopeptidase, dipeptidyl aminopeptidase IV (DAP-IV), sucrase, lactase, and trehalase were studied in 14 different human colorectal cancer cell lines. The effect of sodium butyrate, a known differentiating agent, and cell growth on the activities of these enzymes was also examined. All 14 cell lines exhibited brush border membrane enzyme activities, and in general, the activity of Alkpase, aminopeptidase, and DAP-IV was much higher than the disaccharidases. However, the specific enzyme activities varied among different cell lines. The induction of Alkpase activity by sodium butyrate occurred in most of the 14 cell lines (2- to 123-fold), while induction of the other enzyme activities was observed in several (1.5- to 3.5-fold). In some instances, butyrate caused a decrease in enzyme activity. There was no statistically significant correlation between the induction of Alkpase activity and that of other enzyme activities by sodium butyrate. Levels of aminopeptidase and DAP-IV activity were found to be dependent on cell density and increased 3- to 4-fold by the tenth day in most of the cell lines. Sodium butyrate altered the subcellular distribution pattern of the disaccharidases, causing a significant increase in activity associated with the soluble (cytoplasmic) fraction. Other enzymes such as Alkpase and DAP-IV continued to be predominantly associated with the membrane fraction in butyrate-treated cells. These data suggest that brush border membrane hydrolase activity and the effect of sodium butyrate may provide useful information regarding the differentiation of human colorectal cancer cells.
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PMID:Effect of growth and sodium butyrate on brush border membrane-associated hydrolases in human colorectal cancer cell lines. 400 36

The amounts of lactase (beta-D-galactosidase, EC 3.2.1.23), sucrase (sucrose alpha-D-glucohydrolase, EC 3.2.1.48), maltase (alpha-D-glucosidase, EC 3.2.1.20) microvillus aminopeptidase (EC 3.4.11.2) and dipeptidyl peptidase IV (EC 3.4.14.-) in tangentially sectioned biopsies from jejunum were studied by quantitative immunoelectrophoresis and enzymic assays. All enzymes had their maximum activities near the mid-region of the villi and their lowest activities at the bases of the crypts. The ratio between enzyme activity and immunoreactive protein was constant along the villus-crypt axis. This result is consistent with a continuous brush-border-enzyme synthesis as the enterocytes migrate up the villi.
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PMID:Immunoelectrophoretic studies on human small-intestinal brush-border proteins. 611 34

A largely unrecognized immunoadsorbent desorption technique, hypotonic elution, has been successfully used in the immunoadsorbent purification of the microvillar enzymes aminopeptidase N (EC 3.4.11.2), dipeptidyl peptidase IV (EC 3.4.14.5), sucrase-isomaltase (EC 3.2.1.48-10), lactase-phlorizin hydrolase (EC 3.2.1.23-62) and maltase-glucoamylase (EC 3.2.1.20). This elution method proved capable of achieving an acceptable yield (30-70%) while at the same time preserving the purified enzymes in an enzymically active state. It hereby offers a solution to the problem in immunoadsorbent chromatography of finding an efficient means of elution which is not denaturing to neither the purified enzyme nor the immunoadsorbent column. Common properties of the microvillar enzymes with regard to amphiphilicity, glycosylation or subunit composition could hypothetically account for the similar elution properties of the enzymes but were considered unlikely on several grounds. Hypotonic elution in immunoadsorbent chromatography, therefore, may have a much broader range of applicability, and the method is recommended to be tried out by workers in other areas of protein chemistry.
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PMID:Hypotonic elution, a new desorption principle in immunoadsorbent chromatography. 612 6

Structural changes have been studied during the life cycles of three glycosidases: sucrase-isomaltase (EC 3.2.48-10), lactase-phlorizin hydrolase (EC 3.2.1.23-62), maltase-glucoamylase (EC 3.2.1.20); and three peptidases: aminopeptidase A (EC 3.4.11.7), aminopeptidase N (EC 3.4.11.2) and dipeptidyl peptidase IV (EC 3.4.14.5). The final forms of the enzymes can be divided into at least two groups: the sucrase-isomaltase type, characterized as dimers, which are asymmetric in their hydrophilic parts, have two types of active site and anchor only on one subunit; and the aminopeptidase N type, characterized as dimers, which are symmetric in their hydrophilic part, have only one type of active site and anchor on both subunits. These enzymes are likely to be synthesized on rough endoplasmic reticulum and simultaneously glycosylated into endoglycosidase H-sensitive forms. They are later reglycosylated to endoglycosidase H-resistant forms, which have relative molecular masses similar to the final forms. Enzymes of the sucrase-isomaltase type seem to be synthesized with a polypeptide-chain length corresponding to the sum of both subunits, whereas enzymes of the aminopeptidase N type seem to be synthesized with a polypeptide-chain length corresponding to the constituent subunits themselves. Not much is known about the catabolism of these enzymes. The enzyme activities and the amounts of enzyme protein decrease at the top of the villi, probably due to release into the lumen. The subunits of aminopeptidase N are cleaved by pancreatic proteases to smaller peptides, and sucrase-isomaltase may lose its sucrase polypeptide, while both enzymes remain bound to the membrane.
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PMID:Structure of microvillar enzymes in different phases of their life cycles. 613 6

The longitudinal distribution of the main brush border membrane hydrolases was studied in six entire human small intestine, one of which was found to be lactase-deficient. Sucrase and lactase activities were found to be highest in the jejunum, whereas glucoamylase activity rose steadily and reached its highest activity near the ileocecal valve. Maltase activity distribution was intermediate between that of sucrase and of glucoamylase. Neutral aminopeptidase, acid aminopeptidase and dipeptidyl peptidase IV activities tended to increase toward the end of the small bowel, the latter two activities rising more than the first one. Furthermore, the protein compositions of the brush border membrane in the jejunum and in the ileum were compared after electrophoresis on polyacrylamide gels and crossed-immunoelectrophoresis; protein patterns were found to be similar along the gut, and enzyme-specific activities varied in parallel with the amounts of their corresponding proteins. In the lactase-deficient intestine, the protein band corresponding to lactase was not visible. Maximal digestive capacity was thus localized in the jejunum only for disaccharides, and in the ileum for the more complex substrates, oligosaccharides, and peptides; this finding suggests that the ileum may play a greater role in their terminal digestion than is usually admitted.
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PMID:Longitudinal study of the human intestinal brush border membrane proteins. Distribution of the main disaccharidases and peptidases. 641 75


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