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)

The administration of a carbohydrate-containing diet for 24 hours to rats previously fasted for 3 days led to a twofold increase in total intestinal sucrase and sucrase specific activity. The specific activity of maltase was similarly increased, but lactase activity was unaffected. The sucrose-containing diet led to a greater increase in sucrase than maltase activity, whereas the converse was true of the maltose-containing diet. A carbohydrate-free isocaloric diet led to a slight increase in the total intestinal sucrase, but sucrase specific activity was unchanged. Assay of sucrase activity of mixed homogenates from casein-fed and sucrose-fed rats or fasted and sucrose-fed animals yielded activities that were additive. The Michaelis constant (Km) of the enzyme hydrolyzing sucrose was similar in the fasted, casein-fed, and sucrose-fed rats. The maximal velocity (Vmax) was twice greater in sucrose-fed as compared to casein-fed or fasted rats, suggesting an increased quantity of enzyme subsequent to sucrose feeding. Adrenalectomized rats maintained on 1.0% salt intake had sucrase and maltase levels comparable to those of controls. Steroid administration did not significantly increase their activities. The response to sucrose feeding was similar in both control and adrenalectomized rats, indicative of the absence of steroidal control on sucrase and maltase activity in the adult animal. Studies using intestinal ring preparations indicated that sucrose hydrolysis by the intact cells proceeded more rapidly when animals were fed sucrose. Additional corroboration of the physiologic significance of the increased enzyme levels in homogenates was afforded by intestinal perfusion studies. Sucrose hydrolysis increased twofold and fructose absorption fourfold in animals fed sucrose when compared to either fasted or casein-fed rats.
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PMID:Effect of diet upon intestinal disaccharidases and disaccharide absorption. 601 58

Vitamin D3 is known to stimulate the absorption of calcium across the asymmetric intestinal epithelial cells. Efforts to elucidate the mechanism of stimulation of intestinal calcium transport by vitamin D are now focused on evaluating the protein composition and topology of the brush-border membrane and its associated core material. Intestinal brush-border membranes were isolated from vitamin D-replete and vitamin D-deficient chicks. Core material proteins were isolated, by sedimentation, from brush-border membranes which were solubilized with Triton X-100. As determined by polyacrylamide gel electrophoresis, dietary vitamin D3 treatment caused no change in the relative amounts of five major core material proteins with Mr = 101,000, 94,000, 67,000, 42,000 (actin), and 17,000. In contrast, dietary vitamin D3 treatment caused a significant reduction in the levels of two proteins with Mr = 111,000 (sucrase) and 83,000, and an increase in the levels of a protein with Mr = 78,000 (possibly a subunit of alkaline phosphatase). The Mr = 111,000, 83,000, and 78,000 proteins are readily solubilized by Triton X-100 and are located on the extracellular surface of the brush-border membrane, as judged by [125I]diazoiodosulfanilic acid and lactoperoxidase 125I labeling. A significant vitamin D-dependent difference was found with respect to iodination of isolated core material as evidenced by the 125I labeling patterns of the Mr = 42,000 protein (actin). The Mr = 42,000 protein was labeled two to three times more extensively when associated with core material derived from vitamin D-deficient chicks as compared to vitamin D-replete chicks. Increasing the salt concentration (0-125 mM KCl) present during core material isolation from either vitamin D-replete or vitamin D-deficient chicks yields core material actin which is more susceptible to iodination by both [125I]diazoiodosulfanilic acid and lactoperoxidase. This increase in the extent of actin iodination is coupled to a salt-induced decrease in the stability of the core material which is evidenced by a decrease in the percentage of total brush-border membrane actin which is Triton-insoluble. This strongly suggests that the vitamin D-induced decrease in the accessibility of actin to iodination reagents results from a vitamin D-dependent change in the structure of the core material. Collectively, these results implicate a role for dietary vitamin D3 in maintaining a specified composition and topology of both the brush-border membrane proteins as well as its associated cytoskeletal core proteins, which is possibly important for intestinal calcium transport.
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PMID:Vitamin D. Its effect on the protein composition and core material structure of the chick intestinal brush-border membrane. 630 7

Unsuspected bacterial contamination of the small intestine was indicated by breath hydrogen testing in nine patients aged 2 to 34 months during physical examinations for chronic diarrhea and abdominal pain. Elevated bacterial counts of questionable significance were found in duodenal aspirates before and after antibiotic treatment. There was no evidence of bile salt deconjugation or structural changes in the small intestine by light or electron microscopy. This may indicate that the site of colonization is distal to the biopsy site. Breath testing indicated lactose malabsorption in all patients, and four of five patients tested also malabsorbed sucrose. Duodenal disaccharidase levels in all patients were within the normal ranges, but in eight patients the lactase-sucrase ratio was greatly elevated (0.80 +/- 0.36; normal less than 0.45). Dietary restriction alone did not cause complete cessation of symptoms, whereas all patients responded dramatically to oral antibiotic therapy. When patients were well, the lactase-sucrase ratio had returned to normal in those tested, and all nine had normal lactose and lactulose breath hydrogen tests. Unsuspected bacterial contamination of the small intestine, which is easily detected using the breath hydrogen test, may be more commonly associated with chronic diarrhea in children than has been previously realized. In such cases, therapy should be directed at removing the contamination.
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PMID:Bacterial contamination of the small intestine as an important cause of chronic diarrhea and abdominal pain: diagnosis by breath hydrogen test. 643 89

Rat small intestinal brush border membranes are purified from brush borders by homogenization in relatively high concentrations of thiocyanate salts (0.56 M LiSCN, 0.41 M NaSCN, or 0.52 M KSCN), removal of this salt, and differential centrifugation to separate cytoskeletal material from membranes. The marker enzyme, sucrase, is enriched 98-fold in the final membranes over the starting homogenate of intestinal scrapings at a yield of about 20%. The isolated membranes are capable of secondary active sodium-dependent glucose transport as demonstrated by sodium gradient-supported overshooting glucose uptake.
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PMID:Purification of brush border membrane by thiocyanate treatment. 661 79

The membrane-associated isozyme of invertase (beta-D-fructofuranoside fructo-hydrolase, EC 3.2.1.26) -- precursor of the external glycoprotein invertase (Babczinski, P. and Tanner, W. (1978) Biochim. Biophys. Acta 538, 426-434) - has been purified 60-fold from deoxycholate extracts of derepressed yeast cells. The partially purified enzyme exhibits considerable stability as a salt-free lyophilized powder. Its molecular weight, in this precursor form, has been determined by by sodium dodecyl sulphate (SDS) gel electrophoresis to be 180 000 daltons. This correlates well with the presence of only the inner core carbohydrate parts of the external invertase. The enzyme can be split completely by treatment with endo-beta-N-acetyl-glucosaminidase H from Streptomyces griseus, demonstrating the presence of a di-N-acetylchitobiosyl-asparagine linkage. The proteinaceous split product is still active and has a molecular weight of approx. 120 000. The enzyme cannot be transferred into a supernatant fraction upon osmotic shock treatment of yeast membrane vesicles, indicating that it is strictly membrane-bound. After separation of yeast membranes on a sucrose density gradient, precursor invertase is predominantly associated with two gradient membrane fractions which most probably represent rough and smooth endoplasmic reticulum.
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PMID:Partial purification, characterization and localization of the membrane-associated invertase of yeast. 677 25

Radish beta-fructosidase (beta-D-fructofuranoside fructohydrolase, EC 3.2.1.26) is inactived by diluting the enzyme solution and the activity can be restored by addition of bovine serum albumin or other proteins. The use of detergent, high molar salt solutions or silicone-coated tubes showed that decrease of specific activity upon dilution is not linked to adsorption of the enzyme on to glass walls. Albumin neither protects the enzyme from denaturation by heat nor changes its stability during conservation at room temperature. The action of added proteins is not due to removal of an inhibitor from the enzyme solutions. Some polyanions or polycations have the same effect as albumin, but dialysis or chromatography show that they do not act by reassociation of inactive products formed by dilution of the active enzyme. A molecular weight heterogeneity is observed in the enzyme population when chromatography is performed without albumin. This suggests that inactive forms, formed upon dilution, differ slightly in their molecular conformation from the active forms obtained at high protein concentration.
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PMID:The effect of protein concentration on the activity of beta-fructosidase from radish seedlings. 719 25

When cell-wall invertase (CWI) from Nicotiana tabacum L. cell-suspension cultures, either non-transformed or transformed with Agrobacterium tumefaciens, was salt-eluted from intact cells and purified on Sulfopropyl-Sephadex (SPS) by pH-gradient elution, the enzyme lost about 50% of its activity during a 1-h incubation at pH 4.8. However, Western-blot analysis indicated no appreciable enzyme degradation. Re-chromatography of CWI peak fractions on SPS using NaCl-gradient elution showed the presence of a 17-kDa peptide (p17) in fractions with low CWI activity but strong CWI immunosignal (Weil and Rausch 1994, Planta 193, 430-437). When separating CWI from p17 by Concanavalin A (Con A)-Sepharose chromatography, inhibition could be restored by incubating the inhibitor-containing fraction with inhibitor-free CWI. More than 90% of CWI could be inhibited, suggesting that all CWI was susceptible to p17 binding. The presence of divalent metal ions (Ca2+, Mg2+, Zn2+) during pre-incubation of CWI with p17 reduced CWI inhibition substantially. Also, sucrose protected CWI against inhibition by p17 (half-maximum protection at 1.3 mM). Binding of p17 to CWI during a 1-h pre-incubation was pH-dependent, pH 4.5 causing maximum inhibition, whereas at pH 6.5 no inhibition was observed. Gel-permeation chromatography revealed that the native inhibitor acts as a monomer. Immunoprecipitation of CWI co-precipitated p17, confirming direct binding of p17 to CWI. When fractions containing CWI and p17 were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and subsequent Western blotting a diffuse immunosignal of 86-90 kDa was observed (in addition to the prominent CWI signal at 69 kDa).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A 17-kDa Nicotiana tabacum cell-wall peptide acts as an in-vitro inhibitor of the cell-wall isoform of acid invertase. 776 74

Sodium-dependent bile acid uptake is developmentally regulated in the rat ileum. Transport activity is abruptly expressed on postnatal d 17, although the mechanisms controlling this expression are poorly understood. Changes in bile salt metabolism and hepatic transport result in a marked increase in bile flow before postnatal d 17, and thus this study examined the effects of bile salt feeding on the development of ileal bile acid transport. Twelve-d-old rat pups were gavage-fed saline, taurocholate, or mannitol on a daily basis for 3 d. Sodium-dependent bile acid transport was studied by rapid filtration using ileal brush-border membrane vesicles prepared from the various experimental groups. Taurocholate feeding resulted in precocious development of sodium-dependent bile acid transport and induction of sucrase activity. Mannitol feeding, used as a control for the effects of diarrhea-induced stress, resulted in similar sucrase activity, yet sodium-dependent bile acid transport was induced to only half the level observed in taurocholate-fed animals (3.2 +/- 1.6 versus 6.9 +/- 2.0 pmol/mg protein/45 s, p < 0.001). Serum corticosterone levels were similar in the mannitol- and taurocholate-fed animals (3.8 +/- 1.3 versus 4.6 +/- 1.8 micrograms/dL). Both feedings lead to histologic maturation of the ileum, with a more pronounced effect in the taurocholate-fed pups. Bile salt feeding induces precocious expression of ileal bile acid transport, apparently by both diarrhea-induced stress and a bile salt-specific effect.
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PMID:The effects of bile acid feeding on the development of ileal bile acid transport. 846 58

Arxula adeninivorans Ls3 is described as an ascomycetous, arthroconidial, anamorphic, xerotolerant yeast, which was selected from wood hydrolysates in Siberia. By using minimal salt medium or yeast-extract-peptone-medium with glucose or maltose as carbon source it was shown that this yeast is able to grow at up to 48 degrees C. Increasing temperatures induce changes in morphology from the yeast phase to mycelia depending on an altered programme of gene expression. This dimorphism is an environmentally conditioned (reversible) event and the mycelia can be induced at a cultivation temperature of 45 degrees C. Depending on the morphology of strain Ls3 (yeast phase or mycelia) the secretion behaviour as well as the spectrum of polypeptides accumulated in the culture medium changed. The activities of the accumulated extracellular enzymes glucoamylase and invertase were 2 to 3 times higher in cultures grown at 45 degrees C than in those grown at 30 degrees C. While the level of the glucoamylase protein secreted from mycelia between 45 and 70 hours did not change, biochemical activity decreased after a cultivation time of 43 hours. It was shown that this effect depended on both the catabolic repression of the glucoamylase by glucose and the thermal inactivation of this enzyme in media without or with low concentrations of starch or maltose.
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PMID:Temperature-dependent dimorphism of the yeast Arxula adeninivorans Ls3. 857 79

We reported previously that the absorption of cholesterol and long-chain cholesteryl esters by rabbit small-intestinal brush border membranes (BBMV) is protein-mediated (Thurnhofer, H., and H. Hauser. 1990. Biochemistry. 29:2142-2148; Compassi, S., M. Werder, D. Boffelli, F. E. Weber, H. Hauser, and G. Schulthess. 1995. Biochemistry. 34: 16473-16482). Evidence is presented for similar cholesterol transport activities in rabbit, pig, and human BBMV. As BBMV are subject to a number of limitations and the influence of these on sterol absorption is unknown, it is desirable to verify results obtained with this model system in other brush border membrane models more closely related to the in vivo situation. Sterol absorption in intact enterocytes parallels the absorption measured in BBMV, provided that both model systems are normalized to equal sucrase activity. The parallel behavior of the two brush border membrane models lends support to our previous conclusion that the brush border membrane takes up free and esterified cholesterol in a facilitated and energy-independent process. The absorption of sterols in small-intestinal segments mounted in the Ussing chamber is shown to be a complex process in which the diffusion of the bile salt micelles to the brush border membrane is rate-limiting. All brush border membrane models share the disadvantage of being unstable and subject to degradation. The seriousness of the problem increases apparently with the complexity of the model, i.e., in the order BBMV-->enterocytes-->intestinal segments. One main conclusion of this study is that no brush border membrane model is sufficient and satisfactory, therefore conclusive work in lipid absorption can never be based on a single brush border membrane model.
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PMID:A comparative study of sterol absorption in different small-intestinal brush border membrane models. 897 92


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