Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The [3H] phlorizin-binding component of brush border vesicles was enriched in situ by negative purification. Several procedures, known to effect selective solubilization of membrane components, were used separately or in combination to remove proteins unrelated to the binding. Deoxycholate ruptured the vesicles and released 67% of their protein, thereby increasing the specific [3H] phlorizin-binding activity of the pellet three-to fourfold. Extracting the deoxycholate-pellets with either NaI or alkaline solutions released up to 38% of the deoxycholate-insoluble protein without significantly affecting phlorizin binding. The polypeptide composition of the membranes at the different stages was analyzed by NaDodSO4-polyacrylamide gel electrophoresis. A number of polypeptides present in the original vesicles could be ruled out as essential components of the [3H] phlorizin binding entity. Intact and deoxycholate-treated vesicles were subjected to proteolytic attack. Papain liberated sucrase and isomaltase from intact vesicles, but affected neither other Coomassie-stained bands nor phlorizin binding. Neither the protein composition nor the binding properties of sealed vesicles were influenced by trypsin or chymotrypsin. However, all the proteolytic enzymes tested on deoxycholate-treated membranes substantially reduced [3H] phlorizin binding and produced concomitantly the disappearance of several bands from the electrophoretic profile. Pretreatment of vesicles with papain, followed by deoxycholate extraction and incubation in alkaline media, increased the specific binding activity of the membranes up to ninefold by removing close to 90% of the protein. A limited number of polypeptides are suggested as possible candidates for the glycoside-binding site of intestinal brush borders.
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PMID:Partial purification of the sugar carrier of intestinal brush border membranes. Enrichment of the phlorizin-binding component by selective extractions. 52 29

The effect of graded (5, 10, 20, and 50%) chronic ethanol administration on the intestinal brush border enzymic activities has been investigated in the rat at three levels of the intestinal tract (duodenum, jejunum, ileum). Ethanol has been administered for 8, 15, 30, and 90 days. A 30% to 50% decrease of sucrase and alkaline phosphatase results, showing that the effect of alcohol appears in the first 8 days of intoxication is not reversible after 8 days of an alcohol-free diet. The effect of ethanol is not limited to disaccharidases. Impairment of alkaline phosphatase, peptidases and also enterokinases is observed. The decrease is more marked in the duodenum and jujunum than the ileum. The decrease of enzymic activity is generally maximal after 30 days of intoxication. There is then little further deterioration or even significant improvement. At the 30th day of ethanol administration, a clearcut dose-response relationship has been established. The results obtained suggest that ethanol exerts an effect on the intestinal mucosa which is not directly correlated to morphological villus changes.
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PMID:Intestinal brush border enzymes and chronic alcohol ingestion. 57 90

1. Specimens of human duodenal mucosa were obtained at duodenotomy. Superficial mucosal scrapings were homogenized in isotonic sucrose solution and fractionated by differential centrifugation. The distribution of organelles among the subcellular fractions was monitored by assay of suitable marker enzymes. 2. Enterokinase was recovered predominantly in the nuclear+brush-border fraction and 80% of the total activity was found to be particulate; approximately 20% of the enzyme was present in the soluble fraction, compared with 1% of the brush-border markers sucrase and alkaline phosphatase. 3. The brush-border-containing fraction was subfractionated by treatment with hypertonic Tris followed by differential and density gradient centrifugation. Enterokinase was distributed among the subfractions in parallel with brush-border markers and was concentrated in a subfraction which was highly enriched in microvillous membranes. 4. It was concluded that enterokinase is localized primarily to the microvillous membrane of the epithelial cell brush border in man, but that in addition a proportion of the enzyme may be present in a soluble or easily released form in the duodenal mucosa.
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PMID:Subcellular localization of enterokinase in human duodenal mucosa. 58 40

The effect of dietary amino acids on jejunal sucrase (EC 3.2.1.26) and leucineaminopeptidase (EC 3.4.11.1, LAPase) activities in rats was studied. Rats were force-fed a 10% complete amino acid diet or valine-free diet. The sucrase and LAPase activities in rats force-fed the valine-free diet for 2 days were significantly lower than those in rats force-fed the complete amino acid diet, although the specific activities of these enzymes in the isolated brush border fragment were 10 times higher than those in the mucosa, and most of the activities of these enzymes in the mucosa were localized in the isolated brush border fragment. Results of experiments undertaken to investigate the effects of dietary amino acids during the initial period after the dietary alteration on the sucrase and LAPase activities showed that decreases in the activities of these enzymes in rats force-fed the valine-free diet appeared by 26 hours after the first feed administration; whereas, incorporation of dietary 14C-amino acids administered in the first feed administration into the mucosal protein was significantly lower in rats receiving the valine-free diet than in rats receiving the complete amino acid diet by 7 hours following the first feed administration. These results suggest that decreases in availability of dietary amino acids in the valine-free diet for protein formation in the small intestinal mucosa during the initial period caused the decreases in the sucrase and LAPase activities localized in the brush border membrane.
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PMID:Effect of dietary amino acids on jejunal sucrase and leucineaminopeptidase activities in rats. 66 Mar 2

Functional adaptation of the villus brush border and crypt have been evaluated preceding and following jejunoileal bypass for morbid obesity. Before surgery, 26 of 101 patients who were at least 100% above their ideal weight were randomly included into the study group, and control tissue specimens were collected from the jejunum and ileum. When five patients required revision of the bypass, jejunal and ileal specimens were collected from the functional (included) and nonfunctional (excluded) segments. At 19.2 +/- 5.0 (SD) months following the bypass procedure, there was an increase in alkaline phosphatase, sucrase and thymidine kinase specific activities within the functional remnants; the included ileum demonstrated a greater degree of adaptation than the included jejunum. In the nonfunctional jejunum there was a decrease in alkaline phosphatase and thymidine kinase specific activities, whereas no statistical alteration in mucosal enzyme activities occurred within the nonfunctional ileum. Serum total protein concentrations and serum magnesium levels were also evaluated before bypass and at revision. Mean serum magnesium levels became decreased, whereas serum total protein concentrations were not altered.
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PMID:Functional adaptation of the intestinal mucosal enzymes after jejunoileal bypass for morbid obesity. 66 64

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

A new technique has been developed for the isolation of membrane vesicles from the vitamin D-deficient and vitamin D-treated chick intestinal brush border membrane. The technique involves removal of nuclei from a low speed pellet by discontinuous sucrose gradient centrifugation. The resulting intact brush borders are then homogenized in 0.5 M Tris and the membrane fragments purified on a glycerol gradient. This preparation represents a 20-fold purification of the brush border marker sucrase. After 1alpha-hydroxyvitamin D3 treatment there is a significant increase in membrane phospholipid phosphorous, an alteration in the fatty acid composition of the phosphatidylcholine fraction of membrane phospholipid, and a decrease in sucrase specific activity.
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PMID:Purification and characterization of chick intestine brush border membrane. Effects of 1alpha(OH) vitamin D3 treatment. 67 42

Starvation for 48 hrs reduced the activity of sucrase referred to unit length in rat proximal small intestine by approximately 30%, irrespective of whe her mucosal scrapings, isolated villus epithelial cells or brush border membranes were investigated. Sucrase activity referred to unit weight, unit protein or to unit DNA of intestinal epithelium did not change.
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PMID:Starvation and sucrose activity in small intestinal mucosa. An evaluation of different tissue preparations and reference systems. 68 56

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

When rats are hypophysectomized in neonatal life, the growth of the small intestine is more severely retarded than the growth of the body as a whole. It was shown previously that intestinal growth is not rectified by doses of cortisone and/or throxine that restore normal activity of brush border enzymes in hypophysectomized sucklings; growth hormone did not affect relative weight or enzyme activity. Reexamination of this problem with much lower doses of hormones than previously employed has now shown that relative weight of the intestine is enhanced by cortisone and thyroxine together, and is normalized by cortisone and thyroxine in combination with rat growth hormone. Growth induced by treatment with the three hormones involved increases of crypt depth and villus height, and of mitotic index. Body weight was not affected by hormonal treatment, but the tails of the hypophysectomized sucklings were significantly lengthened by thyroxine alone, the effect being enhanced when growth hormone was also given. The physiological dose of hormones used in the present study were as effective in elevating activity of alkaline phosphatase and sucrase as the larger doses previously used. Cortisone had a greater effect on sucrase, thyroxine on phosphatase. Pentagastrin did not influence either growth or enzyme activity.
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PMID:Hormonal influences on the growth and enzymic differentiation of the small intestine of the hypophysectomized rat. 75 Mar 12


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