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)

Activities of the brush border enzymes alkaline phosphates, leucine aminopeptidase and lactase and the lysosomal enzymes alpha-mannosidase and beta-N-acetylglucosaminidase increased in the serum of newly-born lambs fed colostrum. Feeding lipid and protein components of colostrum and bovine serum resulted in enzyme responses similar to those observed after feeding colostrum. Activities of each of the enzymes increased in mesenteric lymph collected from newly-born lambs when immunoglobulins were being absorbed from the jejunum and ileum.
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PMID:Intestinal brush border and lysosomal enzymes and immunoglobulin absorption in the newly-born lamb. 41 Apr

The effect of intestinal bacterial over-growth on brush border hydrolases and brush border glycoproteins was studied in nonoperated control rats, control rats with surgically introduced jejunal self-emptying blind loops, and rats with surgically introduced jejunal self-filling blind loops. Data were analyzed from blind loop segments, segments above and below the blind loops, and three corresponding segments in the nonoperated controls. Rats with self-filling blind loops had significantly greater fat excretion than controls and exhibited significantly lower conjugated:free bile salt ratios in all three segments. Maltase, sucrase, and lactase activities were significantly reduced in homogenates and isolated brush borders from the self-filling blind loop, but alkaline phosphatase was not affected. The relative degradation rate of homogenate and brush border glycoproteins was assessed by a double-isotope technique involving the injection of d-[6-(3)H]glucosamine 3 h and d-[U-(14)C]glucosamine 19 h before sacrifice, and recorded as a (3)H:(14)C ratio. The relative degradation rate in both homogenate and brush border fractions was significantly greater in most segments from rats with self-filling blind loops. In the upper and blind loop segments from rats with self-filling blind loops, the (3)H:(14)C ratios were higher in the brush border membrane than in the corresponding homogenates, indicating that the increased rates of degradation primarily involve membrane glycoproteins. Incorporation of d-[6-(3)H]glucosamine by brush border glycoproteins was not reduced in rats with self-filling blind loops, suggesting that glycoprotein synthesis was not affected. Polyacrylamide gel electrophoresis of brush border glycoproteins from the contaminated segments indicated that the large molecular weight glycoproteins, which include many of the surface hydrolases, were degraded most rapidly. Brush border maltase, isolated by immunoprecipitation, had (3)H:(14)C ratios characteristic of the most rapidly degraded glycoproteins. The results indicate that bacteria enhance the destruction of intestinal surface glycoproteins including disaccharidases. Since alkaline phosphatase, a glycoprotein, is not affected, the destruction is selective and presumably involves only the most exposed membrane components.
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PMID:Pathogenesis of mucosal injury in the blind loop syndrome. Brush border enzyme activity and glycoprotein degradation. 41 Aug 30

The intestinal brush border disaccharidases separated by gel electrophoresis were studied after oral administration of a high sucrose or lactose diet to 11-day-old suckling rats during 3 days. Some modifications of the brush border protein and eyzyme patterns could be attributed to the effect of the basic diet: increase of glucoamylase, appearance of a weak sucrase activity and of a second molecular form of maltase. However, the specific action of a given disaccharide on the synthesis of the corresponding hydrolytic enzyme could be clearly demonstrated. Indeed, the electrophoretic pattern after sucrose or lactose feeding showed a marked increase of the protein bands corresponding to sucrase-isomaltase or lactase activities.
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PMID:Sucrase and lactase synthesis in suckling rat intestine in response to substrate administration. 41 23

Gluten withdrawal from the diet is occasionally used speculatively in the management of multiple sclerosis. To assess whether there might be any rational basis for such a measure we have undertaken morphological and biochemical studies of the jejunal mucosa in 14 patients with multiple sclerosis. All were found to have morphologically normal villi, and quantitative estimation of surface-to-volume ratios gave values which did not differ from control subjects. Intraepithelial lymphocyte counts were normal. Antigliadin antibody titres were not raised in any patient. Estimation of activity of the brush border disaccharidases (sucrase, lactase, and maltase (showed that the mean level of each enzyme did not differ significantly from control subjects. Analytical subcellular fractionation of the biopsies showed no changes in the distribution or activity of marker enzymes for the brush order, lysosomes, mitochondria, cytosol, peroxisomes, or endoplasmic reticulum. It is concluded that there are no gross morphological or biochemical abnormalities in the jejunal mucosa in patients with multiple sclerosis and, therefore, that the use of gluten-free diets cannot be justified on the assumption that these patients suffer from a coeliac-like lesion of the small intestine.
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PMID:Morphological and biochemical findings in jejunal biopsies from patients with multiple sclerosis. 44 78

The roles of extracellular and intracellular mechanisms in the degradation of brush border proteins have been investigated by studying the small intestinal mucosa of dogs with naturally occurring exocrine pancreatic insufficiency. Peroral jejunal biopsies were homogenised and the organelles separated by isopycnic centrifugation on continuous sucrose density gradients. The distributions of marker enzymes for the principal subcellular organelles were determined in the gradients and related to the specific activities in the homogenates. There were increased activities of the brush border carbohydrases zinc-resistant alpha-glucosidase, maltase and sucrase in the pancreatic insufficient animals, but no change in lactase activity. The activity of gamma-glutamyl transferase was also higher in the affected group; the activities of two other brush border enzymes, alkaline phosphatase and leucyl-beta-naphthylamidase, however, were unaltered. These findings with an increase in the modal density of the brush border from 1.20 to 1.22 are consistent with an enhanced glycoprotein content of the microvillus membrane. There were also rises in the activities of lysosomal enzymes. N-Acetyl-beta-glucosaminidase activity was increased in the soluble fractions and the percentage latent enzyme activity was reduced, findings indicative of an increased fragility of the lysosomal membrane. There were no marked alterations in the activities or density gradient distributions of marker enzymes for the other organelles, stressing the specificity of the changes in the brush borders and lysosomes. These findings are compatible with the degradation of certain exposed brush border proteins by pancreatic proteases and suggest that when this is defective, intracellular degradative mechanisms may be stimulated.
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PMID:Biochemical changes in the jejunal mucosa of dogs with naturally occurring exocrine pancreatic insufficiency. 48 65

A micromethod for the isolation of brush border membrane fragments from single peroral duodenal biopsies, and their subsequent analysis by polyacrylamide gel electrophoresis is described. The quantity of biopsy material used varied between 5 and 15 mg wet weight, leaving enough mucosa for histological examination. By cutting the gels longitudinally into two halves it was possible to identify several maltases, sucrase, isomaltase and lactase and to correlate these enzymatic activities with distinct co-migrating protein peaks. For alkaline phosphatase and enterokinase this correlation was not possible. This method is suitable for the study on single biopsies of the molecular alterations occurring in the various congenital enzyme deficiencies of the human small intestine.
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PMID:A micromethod for separation and identification of digestive enzymes in brush border membrane fragments of single human intestinal biopsies. 66 14

The superiority of human milk as compared with milk of other origin for the feeding of newborns, term or preterm, can be analysed in terms of biological development related to digestive, metabolic and excretory functions during foetal and postnatal life. The macro- and micro-anatomical developments of the intestine are complete in the 6th foetal month. The brush border and some of its enzymes (saccharase-isomaltase) exist already from the 6th foetal week, whereas other enzymes (lactase and intracellular transport enzymes) appear much later. The major gastric and pancreatic enzymes, as well as the synthesis of biliary acids, do not reach maturity until after birth. Several metabolic functions, e.g. the synthesis of cystine from methionine, of tyrosine from phenylalanine, and of urea from ammonia, are still limited at the time of birth. The capacity for excretion of sodium, the osmotic urinary load, and hydrogen ions is suboptimal, especially in the prematurely born. All these circumstances imply that human milk, with its protective properties, represents optimal adaptation to the needs of the child in the perinatal period.
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PMID:Breast feeding and biological development. 69 1

The separation by polyacrylamide gel electrophoresis and subsequent enzymatic analysis of the components of the guinea pig intestinal brush border membrane revealed the presence of three enzyme complexes: maltase-glucoamylase, maltase-sucrase-glucoamylase and maltase-sucrase. Additional bands possessing lactase, trehalase and alkaline phosphatase activity were identified but no phlorizin hydrolase or palatinase was detectable. After exposure to strong dissociating conditions the bands possessing enzymatic activity were either absent or greatly reduced in intensity.
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PMID:Glycosidases of the guinea pig brush border membrane. 86 Dec 25

The incorporation of [14C]glucosamine into brush border glycoproteins by human small intestinal mucosa in organ culture has been investigated. The experiments were based on the observations that (1) isolated brush border membrane fragments from cultured explants showed an unchanged pattern of protein bands and brush border enzyme activities on sodium dodecyl sulfate/polyacrylamide gels after electrophoresis and (2) the rate of overall [14C]glucosamine incorporation measured in the tissue homogenate remained constant up to 48 h. After 24 h of culture, the radioactivity peaks on gels due to incorporation of [14C]glucosamine were found exclusively in the high molecular weight region and corresponded to protein bands identified as maltase-glucoamylase, lactase, sucrase-isomaltase, enterokinase and alkaline phosphatase. Enzymatic activity could not be assigned to the three remaining labelled bands. Most of these glycoproteins were already labelled after 5 h. Newly glycosylated brush border enzymes remained predominantly associated with the brush border membrane of intact cells with little release into the medium up to 24 h.
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PMID:Biosynthesis of brush border glycoproteins by human small intestinal mucosa in organ culture. 88 74

Lactase deficiency, manifested clinically by lactose malabsorption, is often the only biochemical evidence of a residual disturbance of jejunal mucosal function after Escherichia coli enteropathy in the infant. Villous morphology is usually normal. A sustained depression of the processes of biochemical differentiation of lactase biosynthesis has been postulated to explain similar states of lactase deficiency, but a possible influence of altered epithelial cell turnover on the mucosal lactase levels has not been investigated. In ten infants with a residual lactose malabsorption, after E. coli infection, jejunal cell renewal activity and disaccharidase activities were studied by analysis of the exfoliated cells collected by lumenal perfusion. Significant increases in DNA and protein exfoliation and in the brush border activities of sucrase and lactase were observed during recovery from the malabsorptive disturbance. DNA and protein efflux increased almost linearly during a 20-day period. Lactase was initially four times more deficient than sucrase activity in the exfoliated cells. Both enzyme activities increased at almost identical rates. Therefore, it took longer for lactase activity to return to normal levels. The lactase/sucrase ratios approached normal at the end of the 20-day period. The changes in the exfoliating levels of the two enzymes, when analysed in relation to the increases in cell renewal activity, suggested a relationship between sucrase and lactase levels and cell age.
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PMID:Intestinal exfoliated cells in infant diarrhoea: changes in cell renewal and disaccharidase activities. 104 54


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