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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)

A sucrase from honey bees (Apis mellifera) which precipitates between ammonium sulfate saturations of 50 and 70% (5 mg protein per millilitre) and which makes up the major portion of the sucrases of honey bees was purified to homogeneity as shown by several criteria. A large part of the sucrase was found in the head while most of the rest was in the abdomen (a small amount was in the thorax). The enzyme precipitated between the same values of ammonium sulfate saturation as did the sucrase in honey and honey sucrase exhibited kinetics very similar to those of this enzyme. The enzyme was found to be a relatively nonspecific alpha-glucosidase and was shown to have transglucosidase activity. The production of glucose from sucrose was rectilinear when plotted by the Hofstee method at low substrate concentrations but decreased at high sucrose concentrations. The production of fructose was rectilinear throughout the concentration range used. The production of both glucose and rho-nitrophenol when rho nitrophenyl alpha-D-glucoside was the substrate was linear by the Hofstee plot. These effects were found to be due to transglucolysis and a mechanism of action is proposed. Amino acid and amino sugar analyses indicated that the sucrase was a glycoprotein. The molecular weight was found to be between 51000 and 82000 by three different methods and an so20.w value of 4.0 S was obtained. There was no evidence for subunit structure. Tests of the enzyme under various denaturation conditions did not reveal any unusual stabilities. The sucrase bound very tightly to a hydrophobic column. Iodoacetic acid decreased the activity of the sucrase but a large concentration was needed to bring about a 50% activity loss. Reducing agents caused some activity declines. Diethyl pyrocarbonate activated the enzyme.
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PMID:Physical, chemical, and enzymatic studies on the major sucrase of honey bees (Apis mellifera). 0 3

Dextransucrase of Streptococcus sanguis occurred in cell-free and cell-associated forms. Cell-free dextransucrase was purified by four successive chromatographies on Bio-Gel P 60, DEAE-cellulose, and Bio-Gel P 200 from the culture supernatant. The purification of cell-associated dextransucrase was made from the pellet of Streptococcus sanguis culture. Bacterial pellet was extracted with 1 M phosphate buffer (pH 6.0) and chromatographied by using an immunosorbent column. The two enzymes gave single bands in polyacrylamide gel electrophoresis. The molecular weight determined by sodium dodecyl sulfate polyacrylamide gel was about 100 000 daltons for the two forms of dextransucrases. The optimum pH of the cell-free and cell-associated enzymes was around 6 and the temperature optimum was broad for the two enzymes. The KM values for sucrose were respectively 2 mM and 3 mM for cell-free and cell-associated enzymes. When primer dextran was added, the reaction velocity increased but the KM for sucrose remained the same, and the KA for dextran was 200 muM for the two dextransucrases. Trehalose and maltose acted also as glucosyl residue acceptors. Purified enzymes had dextran synthesising activity and invertase-like activity. The same properties of the two forms of enzymes and the positive cross reaction against anti free and anti cell-associated globulins stongly suggest the identity of the two enzymes.
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PMID:Purification and some properties of free and cell-associated dextransucrase from Streptococcus sanguis. 1 37

Invertase, extracted from broken cells of Saccharomyces cerevisiae X-2180 mm2 mannan mutant, was separated into a fraction insoluble in 75% ammonium sulfate (P75 invertase, 36% carbohydrate) and a soluble fraction (S75 invertase, 53% carbohydrate). The latter reacted with antibodies specific for the alpha 1 leads to 6-linked mannose of the mannoprotein outer chain, whereas the P75 invertase failed to react with this antiserum although it did react with serum against terminal alpha 1 leads to 3-linked mannose units that are characteristic of the mannoprotein core. A bacterial endo alpha 1 leads to 6-mannanase removed the outer chains from the S75 invertase and converted it to a form that was similar in electrophoretic and immunochemical properties to the P75 invertase, whereas the endomannanase had little effect on the latter invertase. The results suggest that the P75 invertase is a form of the enzyme to which only the core oligosaccharide units had been added, and the S75 invertase represents an enzyme fraction to which the polysaccharide outer chains were also attached. A strong anomeric PMR signal for unsubstituted alpha 1 leads to 6-linked mannose in the S75 invertase, and a much reduced signal in the P75 invertase and endomannanase-digested S75 invertase, support these conclusions. Endo-N-acetyl-beta-glucosaminidase digestion of the S75 and P75 invertases, as well as of a purified wild type yeast invertase, produced an apparently identical series of 3 to 4 carbohydrate-containing proteins that were separable by polyacrylamide gel electrophoresis in sodium dodecyl sulfate but that migrated as a single band on isoelectric focusing. The bands ranged from about 63,000 to 69,000 daltons and differed by the size of one or more carbohydrate core units each of 15 mannoses and 1 N-acetylglucosamine. The results suggest that the external invertase molecules contain some core units without attached outer chains, and that the cells contain a precursor form of the enzyme to which only the core units have been added. In support of this conclusion, PMR spectra and chromatographic patterns show that the core fragments from the P75, S75, and wild type invertases are essentially identical.
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PMID:Carbohydrate structure of yeast invertase. Demonstration of a form with only core oligosaccharides and a form with completed polysaccharide chains. 11 81

A genetically conditioned mouse model of exocrine pancreatic insufficiency (epi) has been used to study the effect of the absence of lumenal proteases on small intestinal mucosal proteins. The small bowel was divided into eight equal segments. Enzyme activity was increased only in the first three segments in the case of maltase, sucrase, and lactase (all mol wt above 200,000). Alkaline phosphatase (mol wt 145,000), trehalase (mol wt 95,000), and peptidase (mol wt 175,000) activities were unaffected in proximal segments from epi mice. Proximal brush border proteins were identified and measured quantitatively by sodium dodecyl sulfate acrylamide gel electrophoresis. Those enzymes with increased activity were associated with increased amounts of protein in epi mice. Double labeled studies of protein turnover revealed a longer half-life for large brush border proteins (mol wt above 175,000) in epi mice than in normal mice. Enterokinase activity (a marker for duodenal mucosa) was nearly absent from the duodenum of epi mice. Receptors for the intrinsic factor-vitamin B12 complex (markers for ileal mucosal) were present in the ileum equally in normal and in epi mice. Enterokinase activity can be induced in epi mice by feeding its substrate trypsinogen, but not by trypsin or chymotrypsinogen. Epi mice thus retain the ability to synthesize enterokinase. Pancreatic proteases play an important role in the turnover of certain large mucosal proteins and in the induction of enterokinase.
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PMID:Effect of exchange exocrine pancreatic insufficiency on small intestine in the mouse. 20 83

Saccharomyces cerevisiae cells contain a small internal pool of the secretory enzymes invertase and acid phosphatase. This pool increases up to 8-fold at 37 degrees C in a temperature-sensitive, secretion-defective mutant strain (sec 1-1). Cell division and incorporation of a sulfate permease activity stop abruptly at the restrictive temperature, while protein synthesis continues for several hours. Electron microscopy of mutant cells incubated at 37 degrees C reveals a large increase in the number of intracellular membrane-bound vesicles, which are shown by histochemical staining to contain the accumulated acid phosphatase. The vesicles are removed and the accumulated enzymes are secreted when cells are returned to a permissive temperature in the presence or absence of cycloheximide. These results are consistent with a vesicle intermediate in the yeast secretory pathway and suggest that exocytosis may contribute to cell-surface growth.
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PMID:Secretion and cell-surface growth are blocked in a temperature-sensitive mutant of Saccharomyces cerevisiae. 37 86

1. The proteins of the intestinal microvillus membrane have been studied during post-natal development in the rat (days 12--37). 2. In suckling animals (up to age 20 days), the majority of alkaline phosphatase, glucoamylase and lactase activities in the distal half of the intestine were located in the supernatant fraction (100000 X g, 60 min). These enzymes were attached to the membrane from the proximal intestine at all ages. 3. Alkaline phosphatase, maltase and lactase activities in the supernatant fractions chromatographed in Sephadex G-200 in positions similar to the corresponding membrane enzyme. Corresponding activities for lysosomal counter-parts of maltase and lactase present in the supernatant fraction chromatographed differently. Moreover, pH optimum of the soluble enzymes was 9.2 for phosphatase and 5.5--6.0 for glycoamylase and lactase. The soluble lactase and alkaline phosphatase were inhibited minimally by p-chloromercuribenzoate, and sodium fluoride respectively. L-Phenylalanine (20 mM) did inhibit the soluble phosphatase by 90%. Thus, the soluble enzymes are not mainly of the lysosomal origin, but have characteristics of membrane-bound enzymes. 4. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate revealed 18 protein bands which were present in adult membranes. Two other proteins were unique for membranes of distal intestine in suckling rats. The proteins corresponding to known enzyme activity changed as expected with age (e.g. sucrase, maltase increased, lactase decreased). Most of the other proteins were also altered in amount during development. Thus, the changes in the microvillus membrane during development in the rat are not limited to specific enzymes.
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PMID:Development of intestinal brush border membrane proteins in the rat. 41 9

Leuconostoc mesenteroides NRRL B-512(F) was grown in continuous culture under conditions of energy-limited growth. The extracellular enzyme dextransucrase (sucrose: 1,6-alpha-D-glucan 6-alpha-glucosyltransferase EC 2.4.1.5), was not detected in glucose- or maltose-limited cultures. Under conditions of sucrose-limited growth, the enzyme activity of the cell-free culture supernatant increased with increasing dilution rate only after the critical concentration of enzyme inducer (sucrose) in the chemostat had been achieved. The appearance of fructose in the effluent of the sucrose-limited chemostat at higher dilution rates indicated that sucrose was being diverted to dextran biosynthesis. The competition between bacteria and extracellular enzyme for the common substrate sucrose represents an inefficiency in the system of enzyme production. Dextransucrase was isolated from the cell-free culture supernatant by ammonium sulfate precipitation and DEAE-cellulose chromatography. The enzyme preparation exhibited both dextran biosynthetic activity and an invertase-like activity. The biosynthetic efficiency was increased by decreasing the temperature from 30 to 10 degrees C. The enzyme was irreversibly denatured by prolonged incubation in the absence of Ca2+.
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PMID:Dextran biosynthesis and dextransucrase production by continuous culture of Leuconostoc mesenteroides. 45 5

The induction of invertase from beetroot plants and wheat shoots was studied using the "ageing tissues" technique. It was found that ammonium sulfate at concentration 0.001 M enhances invertase induction. This effect of ammonium sulfate was not revealed when the preparations were pretreated by actidione, puromycin and chloramphenicol. A possibility of activation of invertase induction by ammonium sulfate is discussed.
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PMID:[Possible role of ammonium sulfate in inducing invertase biosynthesis in plants]. 65 94

The relationship of the surface properties of a group of anionic surfactants to their effects on intestinal water transport was studied. Dose-response inhibition of water transport in everted hamster jejunal segments was obtained with two long chain detergents (sodium dodecyl sulfate and dioctyl sodium sulfocuccinate), a fatty acid (ricinoleate), and dihydroxy bile salts (deoxycholate, chenodeoxycholate, and taurodeoxycholate), whereas no activity was seen with trihydroxy (cholate, glycocholate, and taurocholate) and tri-keto (dehydrocholate) bile salts. The relative effects on water transport were paralleled by their abilities to lyse the erythrocyte, a membrane model. These two biological effects were related to the surface properties of the agents, as determined by critical micelle concentration and surface tension reduction. We further characterized the action of deoxycholate on hamster small intestine, in vivo. Net water secretion was accompanied by increases in permeability of the mucosa to inulin, dextran, and albumin. These secretory and permeability changes were accompanied by both biochemical and histological alterations: exfoliation (DNA release), membrane effects (sucrase release), and shortened villi. Electron microscopy revealed extensive alteration of the brush border membrane with a decrease in binding of lanthanum and the development of permeability to tracer in villus tip cells. In contrast, taurocholate, which did not alter water transport, did not affect intestinal permeability or the brush border membrane. We believe that the surface properties of anionic surfactants cause changes in absorptive cell membranes which result in intestinal secretion.
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PMID:Effects of anionic surfactants on hamster small intestinal membrane structure and function: relationship to surface activity. 89 48

Free and polystyrene-bound invertase from Saccharomyces cerevisiae were encapsulated within symplex membranes which were composed of cellulose sulfate as the polymeric anion and poly(dimethyldiallylammonium chloride) as the polymeric cation. The kinetics and the performance of the encapsulated enzyme preparations have been compared to the free enzyme employing the hydrolysis of sucrose. The pH and temperature optima were only slightly affected by the encapsulation. The kinetic constants, however, were changed by the encapsulation as a result of diffusional limitation. Encapsulated invertase showed a high storage stability and a high operational stability if low substrate concentrations were applied. The coimmobilization of invertase with living cells, which are not capable of utilizing sucrose, in the described capsules, opens many possibilities in fermentation technology.
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PMID:Immobilization of invertase by encapsulation in polyelectrolyte complexes. 136 31


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