Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Maternal vitamin D deficiency has been shown to lead to reduced body weights in developing rat pups. To evaluate the effects of vitamin D deficiency alone both in dams and pups during the perinatal age on the ontogeny of gastrointestinal enzymes, female weanling rats (3 weeks of age) were divided into three groups. Groups I and II were fed a control (vitamin-D-replete) diet. Group II were fed a vitamin-D-deficient diet. Six weeks afterward they were mated with normal male rats while continuing on their respective diets until sacrifice. Only rats that delivered their pups on the same day from each group were brought into the study. Litter sizes of groups I and II were adjusted to 10, while group III was adjusted to 13 such that the rate of growth paralleled that of group II. At 19 days after birth, all dams and pups were sacrificed. There were no differences in the calcium and phosphorus contents in breast milk obtained from dams of each group. The serum calcium concentration of pups from group II (vitamin-D-deficient) was lower than the other groups. Body weights of pups from groups II and III were significantly lower than those of group I. The mucosal weight, total mucosal protein, mucosal DNA, sucrase, and maltase activities from groups II and III were similar, but lower than group I. Pancreatic weight, total pancreatic protein, DNA, amylase, and lipase activities from groups II and III were also similar, but lower than group I. Vitamin D deficiency was confirmed in both dams and pups from group II.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Vitamin D deficiency, pancreatic and small intestinal enzyme development in rats. 320 79

Current and widely used methods for the isolation and purification of brush-border membranes involve the aggregation of non-brush-border membranes with the divalent cations Ca2+ or Mg2+ with or without subsequent exposure to chaotropic agents (e.g., KSCN). Evidence suggests that these techniques yield morphologically distinct and heterogeneous populations of membranes and that functional differences exist between membrane vesicles prepared by the different procedures, presumably reflecting this heterogeneity. To investigate the effect of the various isolation techniques on the kinetic parameters of D-glucose transport, rat intestinal brush-border vesicles were prepared by each of the following four methods: (i) Ca2+ precipitation; (ii) Ca2+ precipitation with KSCN treatment; (iii) Mg2+ precipitation; and (iv) Mg2+ precipitation with KSCN treatment. Membrane purity as indicated by the enrichment of the enzyme membrane markers sucrase and alkaline phosphatase did not differ between isolation procedures. The Mg-Na-K ATPase activity showed an enrichment factor of less than 1.0 for each of the isolation techniques. D-Glucose uptake was measured with a rapid filtration method under conditions of a zero-trans, 100 mM cis-NaSCN gradient. The membrane preparations yielded similar Hofstee transformations displaying the curvilinear relationship thought to be consistent with the existence of multiple transporters for D-glucose. The average kinetic parameters calculated from the Hofstee plots for each technique were similar. It was concluded that D-glucose transport into rat jejunal membrane vesicles was unaffected by the variation in morphology arising from the technique used to purify the membranes.
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PMID:The effects of different membrane isolation and purification techniques on D-glucose transport into rat brush-border membrane vesicles. 324 73

Oral administration of Gossypol acetic acid (10 mg/kg body wt./day, daily for 15 days), an experimental antifertility agent to male rats, caused significant reduction in the uptake of glucose, alanine, leucine and calcium in the small intestinal segments. Gossypol also caused significant decrease in the intestinal brush border membrane--associated enzymes, sucrase, lactase, maltase and alkaline phosphatase. Kinetic analysis indicated that Gossypol decreased the apparent velocity of the disaccharidases while the Km was not altered. It also caused a shift in the transition temperature in these enzymes and predictably changed the energy of activation both below and above the transition temperature, although the Arrhenius expressions of the temperature dependence still showed proximity and were parallel to the control group.
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PMID:Effects of gossypol acetic acid on the absorptive and digestive functions of rat intestine. 324 43

Intragenic mutations were isolated that suppressed the dominant-lethal phenotype of the YPT1ile121 mutant gene in a temperature-dependent fashion. Among different amino acid substitutions resulting from single point mutations, two, Ala161----Val (A161V) and Met165----Ile (M165I), restored the function of the YPT1ile121 mutant protein. Mutants expressing the YPT1ile121/val161 allele (ypt1ts) only, grew normally at temperatures up to 30 degrees C but were arrested at 37 degrees C. At the restrictive temperature, ypt1ts mutants accumulated ER membranes, small vesicles, and unprocessed invertase, and they exhibited cytoskeletal defects and an enhanced 45Ca2+ uptake. Similar alterations were seen in YPT1-depleted cells. The ypt1ts mutant cells could be rescued from growth arrest by increasing extracellular Ca2+, and, even at the permissive temperature, they displayed increased trifluoperazine sensitivity.
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PMID:Study of a temperature-sensitive mutant of the ras-related YPT1 gene product in yeast suggests a role in the regulation of intracellular calcium. 328 11

We studied 24 patients with end-stage chronic renal failure not treated with hemodialysis (CRF1) and 16 patients on regular hemodialysis (CRF2), to investigate the digestive, absorptive and morphological aspects of the small intestinal mucosa. Serum d-xylose test and biochemical parameters of absorption (serum calcium and proteins) were determined. Jejunal mucosal biopsies were obtained and tissue homogenates assayed for disaccharidases (sucrase, maltase and lactase) and dipeptidases (glycyl-glycinase, leucyl-glycinase and leucyl-aminopeptidase). Histological changes were classified according to the severity of abnormality and compared with biopsies obtained from control subjects. Serum d-xylose test, calcium and proteins were normal in patients with CRF. Maltase specific activity was higher in CRF1 than in controls (p less than 0.05). Lactase and leucyl-aminopeptidase showed a tendency to decrease in CRF, but this difference did not reach statistical significance. Sucrase, glycyl-glycinase and leucyl-glycinase specific activity in CRF was similar to the control group. Histological changes of the small intestinal mucosa of mild to moderate degree were noted in 68% of patients with CRF vs 36% in control subjects (p less than 0.01). No significant difference was noted in the incidence of absorptive, enzymatic (with the exception of maltase) and histological changes between the two groups of patients with CRF. These changes are not influenced by hemodialysis, a long-term treatment averaging 6 months, they appear to represent primary manifestations of CRF and may be related to the nutritional status of patients with CRF.
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PMID:Small intestinal function and structure in patients with chronic renal failure. 339 24

Human serum contains lectins which inhibit the uptake of mannose- and N-acetylglucosamine-terminated glycoproteins by isolated rat hepatic sinusoidal cells. In these experiments, calcium-dependent and calcium-independent human serum mannose-binding proteins have been isolated by affinity chromatography using mannan linked to four different supports. In electroblots both calcium-dependent and -independent serum mannose-binding proteins bound radioiodinated mannan and invertase in the presence of calcium ions, but the binding of calcium-dependent serum mannose-binding proteins was abolished by EDTA. Chicken antibodies were raised against serum mannose-binding proteins and an ELISA was developed. The principal calcium-independent serum mannose-binding protein is mannose-specific IgG as judged by immunodiffusion and electroblotting with anti-human IgG antibodies. The calcium-dependent serum mannose-binding protein is probably the secreted form of an intracellular hepatocyte mannose-binding protein since: antibodies raised against the 30 kDa subunit of the calcium-dependent serum mannose-binding protein also bound 30 kDa subunits of whole liver homogenate and purified human liver mannose-binding protein; antibodies to the human liver mannose-binding protein bound to the 30 kDa subunit of the calcium-dependent serum mannose-binding protein; and the binding specificities of the calcium-dependent serum mannose-binding protein for N-acetylglucosamine and fucose as well as mannose, and its recognition of the core region of an oligosaccharide rather than only the peripheral sugars, were identical to those reported for the hepatocyte mannose-binding protein. The physiological ligands of these serum mannose-binding proteins are unknown but they could bind noxious glycoproteins which enter the circulation prior to their removal by the sinusoidal mannose receptor.
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PMID:Mannose-binding proteins in human serum: identification of mannose-specific immunoglobulins and a calcium-dependent lectin, of broader carbohydrate specificity, secreted by hepatocytes. 374 82

The apical membranes of rabbit gallbladder epithelial cells were isolated by treating the homogenate with Ca2+ or Mg2+ and centrifuging the suspension in Percoll gradient. In this way brush-border membranes were obtained with enrichment factors ranging between 10 and 20 and yields of 15-30%. A second method is described with which membranes were isolated, without any preliminary treatment, first by differential centrifugation, then with Percoll gradient; the final membrane enrichment was over 15, however the yield was very low (3%). Many possible enzymatic markers of the apical plasma membrane were investigated: L-gamma-glutamyltransferase, alkaline phosphatase, leucine aminopeptidase, sucrase. The first appears to be that of choice. Apical membrane fraction could be also evidenced by autofluorescence or by labeling with Lotus tetragonolobus lectin. Preliminary experiments showed that apical plasma membranes isolated in this way form vesicles.
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PMID:Isolation of apical plasma membrane in rabbit gallbladder epithelium by Percoll density gradient centrifugation. 381 91

We studied the postnatal development of bile acid transport in rat ileum, using brush border membrane vesicles prepared by a Ca2+ precipitation method. Membrane vesicles from developing (day 14-21) and adult Sprague-Dawley rats were enriched to a similar degree in brush border membrane marker enzyme activities (sucrase or lactase) compared with homogenate. Uptake of 25 microM [3H]taurocholate by adult membrane vesicles was markedly accelerated in the presence of an inwardly directed 100 mM Na+ gradient compared with a K+ gradient, and there was a transient intravesicular accumulation of isotope above equilibrium ("overshoot"). In contrast, at 14 and 16 days of age there was no difference in taurocholate uptake in the presence of a Na+ or a K+ gradient, and uptake was not saturable. The integrity of the vesicle preparation from 14- and 16-day-old rats was confirmed by the demonstration of Na+-dependent uphill transport of 100 microM L-[3H]alanine. Stimulation of taurocholate uptake by a Na+ compared with a K+ gradient ("sodium effect") was first observed at age 17 days, but an overshoot was not present until 18 days of age. The initial rate of Na+-dependent taurocholate (25 microM) uptake increased sixfold between 17 and 21 days of age (24.36 +/- 6.11 to 148.59 +/- 8.56 pmol X mg-1 protein X 5 s-1). Absent or decreased Na+-dependent taurocholate uptake was not due to increased permeability or "leakiness" of vesicles from younger animals to Na+. Ileal brush border membrane vesicles demonstrated saturable kinetics at 21 days, but the Vmax was significantly lower (10.15 +/- 0.44 vs. 13.42 +/- 0.59 nmol X mg-1 protein X min -1, p less than 0.001) and the apparent Km higher (130.6 +/- 18.9 vs. 70.1 +/- 12.6 microM, p less than 0.007) than the adult. We conclude that (a) saturable, Na+-bile acid coupled transport is absent in rat ileum throughout most of the suckling period and (b) kinetic analysis suggests that maturation occurs near weaning, primarily through an increase in functional bile acid carriers within the ileal brush border membrane.
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PMID:Ontogeny of bile acid transport in brush border membrane vesicles from rat ileum. 395 37

The effect of unavailable carbohydrates on the intestinal absorption of calcium was studied in rats raised for 7 or 8 weeks on diets containing 10 or 20% of cellulose, glucomannan, or pullulan. The following results were obtained a) Body weight gain was diminished more severely in glucomannan groups than in cellulose groups. b) Serum calcium levels were slightly lower in all groups fed unavailable carbohydrates, whereas serum inorganic phosphorus levels were similar to that of the control group. c) There was a significant reduction of bone ash from rats fed glucommanan or cellulose with 620 glycoside bonds. d) Calcium transport measured in the everted duodenal sac remarkable decreased in the glucomannan 20% group, but slightly increased in the cellulose groups. e) Calcium binding activity was lowered significantly in all groups fed unavailable carbohydrates. f) Alkaline phosphatase and sucrase activities in the duodenum were also markedly decreased by prolonged intake of unavailable carbohydrates. These results indicate that inhibitory effect of unavailable carbohydrates on intestinal calcium absorption is partially due to the loss of calcium binding protein caused by gastrointestinal transit of large amounts of undigested substances.
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PMID:Mechanism of inhibitory effect of unavailable carbohydrate on intestinal calcium absorption. 627 11

Brush-border-membrane vesicles isolated from hamster ileum were incubated with either papain or Pronase P and subsequently centrifuged to obtain soluble (supernatant) and insoluble (pellet) fractions. Papain (4 units/ml) solubilized 95--100% of the sucrase and leucine naphthylamide-hydrolysing activities but only 30% of the alkaline phosphatase. Digestion with papain also resulted in the solubilization of more than 75% of the ileal receptor for intrinsic factor-vitamin B-12 complex with a corresponding decrease in receptor activity in the pellet. Essentially 100% of the receptor activity was recovered. In contrast, digestion with Pronase P resulted in a decrease in total receptor activity. Papain-solubilized receptor was not sedimented by centrifugation at 105 000 g for 90 min and was eluted in the included volume of Sepharose 6B. Like the binding to more intact preparations, binding of intrinsic factor-vitamin B-12 complex to papain-solubilized receptor was rapid, reaching 50% of maximum in 8 min, and required Ca2+. Although Mg2+ could not completely substitute for Ca2+, Mg2+ did stimulate Ca2+-dependent binding at low Ca2+ concentrations. These results demonstrate that the ileal receptor for intrinsic factor-vitamin B-12 complex can be solubilized with papain, and suggest that papain solubilization may be a useful first step in the isolation and purification of this receptor.
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PMID:Solubilization of the ileal receptor for intrinsic factor--vitamin B-12 complex by digestion with papain. 628 Jun 80


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