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)

Sucrose dissimilation was studied in five strains of Streptococcus mutans. Glucose-adapted strain SL-1 makes acid more slowly from sucrose than from glucose; glucose-adapted strain SL-1 gives diauxie growth kinetics in broth containing limiting amounts of both glucose and sucrose. Thus, at least part of the sucrose dissimilative system appears inducible. Sucrase activity was identified in the 37,000 x g soluble cell fraction of five strains. Its intracellular location implies the presence of sucrose permease. The specific activity of the sucrase is higher in sucrose-adapted cells than in cells adapted to glucose or other sugars, further suggesting its inducibility. The enzyme from strain SL-1 was partially purified by diethylaminoethyl-cellulose chromatography and shown to be a single molecule with a molecular weight of about 48,000. The partially purified enzyme is specific for sucrose and produces equimolar glucose and fructose. Since it degrades raffinose, but not melezitose or other alpha-glucosides, it is an invertase. The invertase has a relatively high K(m) for its substrate and a pH optimum of 5.5 to 6.2. It is activated by inorganic orthophosphate (P(i)), P(i) functioning as a positive effector. Arsenate can substitute for phosphate. Neither the crude cell-free extract nor the partially purified enzyme preparations has detectable sucrose phosphorylase activity. A possible potent role of the invertase in the regulation of sucrose carbon flow in S. mutans is discussed.
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PMID:Identification, preliminary characterization, and evidence for regulation of invertase in Streptococcus mutans. 474 13

The specific effect of dietary sugars on jejunal disaccharidase activity in seven normal nonfasted male volunteers was studied. The sugars tested were sucrose, maltose, lactose, glucose, fructose, and galactose. Comparisons were made of the effects of each sugar in an isocaloric liquid diet. In all subjects, sucrose feeding, as compared to glucose feeding, significantly increased jejunal sucrase (S) and maltase (M) activities, but not lactase (L) activity. The S/L and M/L ratios increased to a significant degree. Fructose feeding, in two subjects, gave results similar to sucrose when comparing fructose and glucose diets. One subject was fed lactose, galactose, and maltose. These sugars, compared to glucose, did not increase disaccharidase activity. Fructose appears to be the active principle in the sucrose molecule. These results demonstrate that specific dietary sugars can alter enzyme activity in the small intestine of man in a specific fashion. Sucrose and fructose are able to regulate sucrase and maltase activity. Dietary alteration of intestinal enzymes may represent a suitable system for studying the regulation of enzyme activity in man.
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PMID:Control of jejunal sucrase and maltase activity by dietary sucrose or fructose in man. A model for the study of enzyme regulation in man. 567 20

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

The digestive (hydrolytic enzymes) and absorptive (sugar and amino acid transport) functions of dog small intestine have been evaluated in different segments and analysed in relation to morphometric and biochemical parameters. The dog small intestine is a cylinder of decreasing diameter in which the underlying mucosa thins down from duodenum to ileum, though maintaining its cellular homogeneity as revealed by measuring the mucosal weight, the total DNA and protein content and the protein content of the brush border membrane. Sucrase, gamma-glutamyltranspeptidase, leucylnaphthylamidase and alkaline phosphatase specific activities, measured both in homogenates of the mucosa and purified brush border membrane fractions, were found distributed along proximo-distal gradients of activity. However, different patterns were obtained which are specific for the enzyme considered. Kinetic parameters, Vmax and Km, were estimated for sucrase and alkaline phosphatase in purified brush border membrane fractions. It appeared that Vmax correlated well with the observed distribution of catalytic sites along the small intestine. Sugar (glucose) and amino acid (alanine and leucine) transport capacities were also distributed according to specific proximo-distal gradients but passive and facilitated diffusions were not affected. Only the active, Na+ -dependent component of transport was sensitive to position along the small intestine and we postulated that this adaptation should involve variations in carrier densities. It is therefore concluded that absorbo-digestive functions are intrinsic characteristics of the brush border membrane which are regulated according to the position along the small intestine.
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PMID:Digestive and absorptive functions along dog small intestine: comparative distributions in relation to biochemical and morphological parameters. 614 47

Secretion of acid phosphatase and invertase was examined in an inositol-requiring ino1 mutant of the yeast Saccharomyces cerevisiae. Inositol starvation is known to block plasma membrane expansion, presumably due to restricted membrane phospholipid synthesis. If membrane expansion and extracellular protein secretion are accomplished by the same intracellular transport process, one would expect secretion to fail coordinately with cessation of plasma membrane growth in inositol-starved cells. In glucose-grown, inositol-starved cells, plasma membrane expansion and acid phosphatase secretion stopped coordinately, and intracellular acid phosphatase accumulated. In sucrose-grown, inositol-starved cells, plasma membrane growth halted, but secretion of both acid phosphatase and invertase continued until the onset of inositol-less death. Although glucose-grown and sucrose-grown cells differ in their ability to secrete when deprived of inositol, they exhibited the same disturbances in phospholipid synthesis. Phosphatidylinositol synthesis failed, and its precursors phosphatidic acid and CDP-diglyceride accumulated equally in both cultures. Sucrose-grown yeast cells appear to accomplish normal levels of extracellular protein secretion by an inositol-independent mechanism. In glucose-grown yeasts, both plasma membrane expansion and secretion are inositol dependent.
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PMID:Secretion can proceed uncoupled from net plasma membrane expansion in inositol-starved Saccharomyces cerevisiae. 638 2

Sucrose (100 g) loading tests were performed in 10 healthy volunteers before and during the intake of an alpha-glucosidehydrolase inhibitor (acarbose) for 8 weeks (3 X 200 mg daily) and serum levels of glucose, immunoreactive insulin (IRI), and immunoreactive gastric inhibitory polypeptide (IR-GIP) were measured. The addition of 200 mg of acarbose to the sucrose load attenuated the sucrose-induced glycaemia and IRI response and completely abolished the IR-GIP release. The volunteers complained about meteorism and abdominal pain during the intake of the inhibitor. These side effects became less marked at the end of the study. The attenuation of complaints cannot be explained by a decreasing sucrase inhibition, since the increase of glucose, IRI, and IR-GIP after sucrose loading at the beginning and after 4 and 8 weeks was equally impaired by acarbose.
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PMID:Response of serum levels of gastric inhibitory polypeptide and insulin to sucrose ingestion during long-term application of acarbose. 703 56

Organoleptic and some of the chemical parameters of sugar honey were compared with those of nectar beehoney. Rapid methods were devised to determine the main parameters characteristic of the soundness of beehoney. It was found that beehoney containing over 7% of saccharose may be regarded as feed, immature or sugar-falsified. In natural beehoney, the amount of saccharose, amylase (diastase) and invertase mainly depends on the degree of maturation and physiological status of the bee families during yield of honey. Sugar honey is characterized by the increased content of saccharose and water, reduced quantity of inverted sugar and low diastase activity.
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PMID:[Criteria for distinguishing sugar-adulterated honey from the natural]. 707 84

A rat jejunal segment of 15 cm length was perfused single pass with a 3 mmol/l sucrose solution 4 times daily at 8.00, 14.00, 20.00 and 2.00. One group of rats was fed ad libitum, a second group was "meal fed" between 14.00 and 18.00. Sucrose absorption reached its maximum at 8.00 in the rats fed ad libitum whereas it was spread over a period of six hours (20.00-2.00) in the meal fed rats. The activity of sucrase in mucosal scrapings reached its peak at feeding time.
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PMID:[Circadian variation of intestinal sucrose and water absorption in rats (author's transl)]. 723 33

An oral sucrose tolerance test was performed in a group of 103 children, aged between 3 months and 15 years because of episodic diarrhea and/or abdominal pains. Sucrose malabsorption defined as an abnormal increase in expired hydrogen, was found in only 3 children who suffered from congenital sucrase-isomaltase deficiency. This 1% incidence of sucrose malabsorption was lower than the incidence of lactose malabsorption found in this group (33%). Mean rise in blood glucose during the sucrose test was higher (3.4 +/- 1.4 vs. 2.4 +/- 1.2 mmol/l, p less than 0.0001) and the occurrence of false flat blood glucose curves was lower (3% vs. 12.8%, p less than 0.05) than during the lactose test. These findings are consistent with the higher sucrase activity in the small bowel mucosa compared to lactase. In contrast to the lactose tolerance test, sucrose tolerance test should not be used as a screening procedure for secondary disaccharidase deficiency in children.
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PMID:Diagnostic value of sucrose tolerance test in children evaluated by breath hydrogen measurement. 736 16

Glycosidases and glycosyltransferases were electrophoresed in the presence of sodium dodecyl sulfate (SDS) in a thin-layer gel supported by a glass plate, treated with the nonionic detergent Triton X-100, and specifically stained for the sugar-releasing activity of these enzymes. Staining is based on conversion of monosugars or a sugar phosphate to glucose-6-phosphate by the appropriate intermediary enzymes, reduction of NADP+ to NADPH, and accumulation of reduced Nitroblue Tetrazolium in the gel. Among the enzymes tested, alpha-glucosidase, beta-glucosidase and beta-mannosidase could not be renatured, whereas beta-fructofuranosidase and alpha-mannosidase could be renatured unless heated before electrophoresis. Sucrose phosphorylase, glucosyltransferase and fructosyltransferase, which are single-peptide proteins with no cystine bond, could be renatured even after pretreatment with SDS and/or mercaptoethanol at 100 degrees C for 10 min. However, exclusive heating remarkably decreased the activities of these enzymes. Two-dimensional separation of the five renaturable enzymes was done in a single thin-layer gel, using SDS-electrophoresis in the first dimension and isoelectric focusing in the second dimension.
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PMID:Renaturation and activity staining of glycosidases and glycosyltransferases in gels after sodium dodecyl sulfate-electrophoresis. 752 70


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