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

The suitability of the simultaneous azocoupling reaction with 1-naphthyl-beta-D-glucoside and hexazonium-p-rosanilin in the detection of the activity of lactase (or lactase-beta-glucosidase complex) in jejunal biopsies of patients with various forms of the malabsorption syndrome was tested. Results were compared with those obtained with the indigogenic method using 4-Cl-5-Br-3-indolyl-beta-D-fucoside which is the method of choice. Both methods gave identical results as far as the relative intensity of the brush border staining was concerned. The azocoupling method applied in unfixed cold microtome sections can be recommended for the routine diagnostics of the malabsorption syndrome when the indolyl substrate is not available.
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PMID:Suitability of the azocoupling reaction with 1-naphthyl-beta-D-glucoside for the histochemical demonstration of lactase (lactase-beta-glucosidase complex) in human enterobiopsies. 5 35

Rotaviruses are now regarded as important causes of diarrhoea in man, cattle, pigs, mice, and possibly other animals. Characteristically, disease occurs in newborn and young animals, and infection seems limited to the differentiated gut epithelial cells. The major surface polypeptide of the calf scours rotavirus is glycosylated, and highly purified beta-galactosidase (lactase) interacts with the virus in vitro causing removal of the outer shell of the capsid (uncoating). It is suggested that lactase present in the brush border of the intestinal epithelial cell performs a similar function in vivo by acting as a combined receptor and uncoating enzyme for the rotavirus. This hypothesis is consistent with the observations that rotaviruses seem to infect only gut epithelial cells, and that infant animals, whose lactase concentrations are generally higher than those of adult animals, seem more susceptible to rotavirus infections. Implications of the hypothesis include possible new approaches to laboratory cultivation of rotaviruses, which should be more successful in cells selected for surface lactase activity, and the suggestion that the epidemiology of human rotavirus infections may be influenced by the fact that different ethnic groups have different lactase levels (and hence lactose intolerance) in adulthood.
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PMID:Is lactase the receptor and uncoating enzyme for infantile enteritis (rota) viruses? 5 21

An azoindozyl method for the histochemical demonstration of lactase (lactase-beta-glucosidase complex) is described. The incubation medium consists of 5 mg 5-Br-4-Cl-3-indolyl-beta-D-fucoside (dissolved in 0.5 ml N,N-dimethylformamide) and 0.02 ml hexazotized prosaniline in 10 ml 0.1 M citric acid phosphate buffer, pH 6-6.5. By means of this method lactase can be exactly localized in the brush border of the enterozytes in the jejunum of suckling rats. Compared to the corresponding indigogenic method the azoindoxyl reaction proceeds faster and the reaction product is often precipitated more precisely.
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PMID:[Azoindoxyl methods for the histochemical investigation of hydrolases. I. Lactase (lactase-beta-glucosidase complex) (author's transl)]. 6 Mar 19

Dog enterocyte brush border proteins have been studied after a 75% proximal resection of the small bowel. This study was carried on microvillar membrane preparations purified from ileal mucosa sampled before and after regeneration on neighbouring intestinal segments, each animal acting as its own control. After six weeks of regeneration a statistically significant decrease of the following enzyme specific activities was observed: lactase, cellobiase, maltase, sucrase, palatinase, dextranase, trehalase, alkaline phosphatase, aminopeptidase and gamma-glutamyl transferase. Analysis of brush border proteins by polyacrylamide gel electrophoresis in presence of sodium dodecyl sulphate have shown after regeneration a decreased rate for the proteins with a molecular weight higher than 100,000 daltons. Modifications of electrophoretic patterns seem to be related to the specific activity decreases observed for brush border enzymes after regeneration, since the molecular weight of these enzymes were found between 116,000 and 285,000 daltons, after gel filtration.
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PMID:Effect of massive proximal small bowel resection on intestinal brush border membrane proteins in the dog. 8 27

The presence of antigenic determinants of the following enzymes was detected in enterocytes by the indirect immunofluorescence method: 1. lactase in human biopsy material, 2. sucrase-isomaltase during ontogenesis in the rat. 1. Lactase: The antigenic relationship between rat and human lactase, demonstrated with the isolated enzymes, was utilized for the histochemical localization of human lactase. The indirect immunofluorescence method, using guinea pig antiserum to rat lactase, demonstrated the presence of human lactase in the enterocyte brush border. The usefulness of this method for clinical practice resides in the possibility of detecting enzymatically inactive protein immunologically related to lactase in cases of lactase deficiency, thereby facilitating more detailed classification of these diseases. 2. Sucrase-isomaltase: Guinea pig antiserum to rat sucrase-isomaltase (SI) was prepared. It was used to demonstrate antigenic determinants of the enzyme in the enterocyte brush border of the rat during ontogenesis. Structural SI protein is already present in 3-day-old rats, whereas enzyme activity can first be demonstrated histochemically from the 11th day of life and biochemically, in vitro, not until about the 18th day. We consider that this technique can be used for studying the biogenesis of membrane-bound enzymes.
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PMID:Immunohistochemical localization of intestinal glycosidases. 9 28

Membrane-bound enzymes have certain specific differences compared with soluble enzymes. Membrane-binding often enables greater catalytic activity of associated enzymatic reactions, their regulation by low molecular weight substances (substrates and allosteric effectors, hormones) and compartmentation, etc. On the other hand, the binding of enzymes to membranes causes considerable difficulties as regards their isolation and the determination of their homogeneity and substrate specificity. Membrane enzymes provide a unique opportunity for studying the biogenesis of membranes and their physiological properties, however. These problems are discussed in relation to two types of membranes--the inner mitochondrial membrane and the membrane of the brush border of the small intestine. An example of the utilization of immunochemical methods is given in the results of a study of biosynthesis of the cytochrome oxidase complex in yeast cells. In the case of the brush border of the mammalian small intestine, the fact that certain enzymes, which are also of clinical significance from the aspect of congenital genetic defects, can be isolated only as complexes, constitutes a very real problem. This applies particularly to the sucrase-isomaltase complex and the lactase-beta-glucosidase complex. Solving questions of substrate specificity is of significance for the choice of a suitable analytical or histochemical method. The common regulation of these complexes gives an insight into the problems of membrane biogenesis, however. Immunochemical methods can be employed as sensitive criteria to support biochemical and morphological studies. Collaboration between the biochemist and histochemist proved especially valuable when determining the substrate specificity of enzymes (glycosidases) in relation to histochemical substrates, when applying histochemical methods for detecting enzymatic activity in immunoprecipitates and acrylamide gels and in immunohistochemical studies of the localization and developmental differentiation of the enzymes of the brush border of the small intestine.
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PMID:Biochemistry and immunochemistry of membrane-bound enzymes. 9 30

A considerable increase occurs in D-glucose uptake and brush border sucrase and lactase activities in the intestine of monkeys treated with a single oral dose of DDT. Brush border alkaline phosphatase activity remains unaffected in the pesticide treated animals. In vitro addiction of DDT has no effect on the sugar absorption and disaccharidase activities.
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PMID:Effects of DDT (chlorophenotane) administration on glucose uptake and brush border enzymes in monkey intestine. 9 80

Using freeze-dried or sections from fresh-frozen or aldehyde-fixed material nitro BT (NBT), tetranito BT (TNBT), distyryl nitro BT (DS-NBT), thiocarbamyl nitro BT (TC-NBT) or benzothiazolylstyrylphthalhydrazidyl tetrazolium chloride (BSPT) were tested as auxiliary reagents for the localization of glycosidases, phosphatases and non-specific esterases with indoxyl substrates in rat tissues. By means of NBT or TNBT as a tetrazolium salt acid beta-D-galactosidase, beta-D-N-acetylglucosaminidase, acid phosphatase, neuraminidase and non-specific esterase can only be localized at the cellular level; a more precise localization is possible for lactase-beta-D-glucosidase in the intestinal brush border, and the best results are obtained in the demonstration of alkaline phosphatase; among all methods described previously the tetrazolium procedure with TNBT is the method of choice for the light microscopic localization of this enzyme. Reverse data are observed with BSPT as a tetrazolium salt; then, all acid and neutral hydrolases can be exactly localized in lysosomes, secretion granules, cytoplasm and/or microvilli of many cells and tissues provided BSPT-formazan is stabilized by osmification. Furthermore, this procedure enables the reliable ultracytochemical demonstration of these enzymes. However, in the case of alkaline phosphatase only sites with high enzyme activity reveal a positive reaction. -DS- and TC-NBT are inferior to NBT, TNBT or BSPT.
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PMID:[Tetrazolium methods for the histochemical investigation of hydrolases (author's transl)]. 10 69

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


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