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

The effect of intestinal bacterial over-growth on brush border hydrolases and brush border glycoproteins was studied in nonoperated control rats, control rats with surgically introduced jejunal self-emptying blind loops, and rats with surgically introduced jejunal self-filling blind loops. Data were analyzed from blind loop segments, segments above and below the blind loops, and three corresponding segments in the nonoperated controls. Rats with self-filling blind loops had significantly greater fat excretion than controls and exhibited significantly lower conjugated:free bile salt ratios in all three segments. Maltase, sucrase, and lactase activities were significantly reduced in homogenates and isolated brush borders from the self-filling blind loop, but alkaline phosphatase was not affected. The relative degradation rate of homogenate and brush border glycoproteins was assessed by a double-isotope technique involving the injection of d-[6-(3)H]glucosamine 3 h and d-[U-(14)C]glucosamine 19 h before sacrifice, and recorded as a (3)H:(14)C ratio. The relative degradation rate in both homogenate and brush border fractions was significantly greater in most segments from rats with self-filling blind loops. In the upper and blind loop segments from rats with self-filling blind loops, the (3)H:(14)C ratios were higher in the brush border membrane than in the corresponding homogenates, indicating that the increased rates of degradation primarily involve membrane glycoproteins. Incorporation of d-[6-(3)H]glucosamine by brush border glycoproteins was not reduced in rats with self-filling blind loops, suggesting that glycoprotein synthesis was not affected. Polyacrylamide gel electrophoresis of brush border glycoproteins from the contaminated segments indicated that the large molecular weight glycoproteins, which include many of the surface hydrolases, were degraded most rapidly. Brush border maltase, isolated by immunoprecipitation, had (3)H:(14)C ratios characteristic of the most rapidly degraded glycoproteins. The results indicate that bacteria enhance the destruction of intestinal surface glycoproteins including disaccharidases. Since alkaline phosphatase, a glycoprotein, is not affected, the destruction is selective and presumably involves only the most exposed membrane components.
J Clin Invest 1977 Dec
PMID:Pathogenesis of mucosal injury in the blind loop syndrome. Brush border enzyme activity and glycoprotein degradation. 41 Aug 30

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.
J Membr Biol 1979 Dec 12
PMID:Partial purification of the sugar carrier of intestinal brush border membranes. Enrichment of the phlorizin-binding component by selective extractions. 52 29

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.
Clin Sci Mol Med 1977 Dec
PMID:Subcellular localization of enterokinase in human duodenal mucosa. 58 40

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.
Growth 1978 Dec
PMID:Hormonal influences on the growth and enzymic differentiation of the small intestine of the hypophysectomized rat. 75 Mar 12

The effect of 8-hydroxyquinoline, a rapid inhibitor of RNA synthesis, was followed on the activity of a number of enzymes in cultures of the fission yeast Schizosaccharomyces pombe. Two types of effect were found. In the first the activity continued to rise for a period and then remained constant. This occurred with alkaline phosphatase, basal and derepressed acid phosphatase, hexokinase, and derepressed sucrase and maltase at low cell density. It is consistent with control being exercised by an unstable mRNA or by an unstable stimulator of translocation. In the second the activity increased above the control values for several hours. This occurred with basal sucrase and maltase, and suggests a stable mRNA and an unstable inhibitor of translation. The extent of 'superproduction' of sucrase varied with cell density and with growth medium and this may be due to differences in the degree of translational inhibition. The possiblilty of a stable mRNA has interesting implications for the control of enzyme synthesis through the cell cycle.
Eur J Biochem 1975 Dec 15
PMID:The effect of 8-hydroxyquinoline on enzyme synthesis in the fission yeast Schizosaccharomyces pombe. 81 99

Carbon assimilation by Claviceps purpurea, growing as a parasite on cereals, has been investigated by supplying the host plant with 14CO2 in a closed system. The presence of the pathogen induced the plant to exude photosynthate which contained high levels of sucrose. During the period of 14CO2 supply, 14C was incorporated into the sucrose and so the path of carbon into the parasite could be traced. Hexoses, derived by the action of the fungal sucrase on sucrose, were assimilated by the pathogen and largely converted into polyols - mainly mannitol and, to a lesser extent, trehalose. The rate of carbohydrate metabolism decreased with maturation of the ergot, and also showed qualitative differences between the basal and apical regions of the ergot which were probably a function of nutrient supply.
J Gen Microbiol 1976 Dec
PMID:Carbon assimilation by Claviceps purpurea growing as a parasite. 101 Oct 13

Intervase from extracellular culture fluids of S. mutans strain SL-1 was shown to have the same characteristics as intracellular invertase from the same strain. The data indicate that intracellular invertase is released into the culture fluids primarily during the late log and stationary phases of growth.
Experientia 1975 Dec 15
PMID:Invertase in cell-free culture fluids of Streptococcus mutans strain SL-1. 121 52

Enzymic hydrolysis of di-D-fructofuranose 1, 2'; 2, 3' dianhydride with the bacteria Arthrobacter ureafaciens was studied to elucidate its mechanism. Hydrolysis of the difructose dianhydride to D-fructose, which did not occur with yeast invertase [EC 3.2.1.26], was found to occur on incubation with an enzyme preparation from an autolysate of the above bacteria. However, incubation with enzyme which had been treated at 60 degrees for 30 min yielded an intermediate hydrolysis product. The product isolated was found to be inulobiose and to be hydrolyzed to D-fructose by the original enzyme, as well as by yeast invertase. It was thus shown that the hydrolysis of the difructose dianhydride to D-fructose with the crude enzyme took place not in a single step but in two separate steps at 2, 3' and 1, 2' linkages. It was not determined whether the entire process is mediated by one and the same beta-fructofuranosidase or by different enzymes.
J Biochem 1975 Dec
PMID:Enzymic hydrolysis of di-D-fructofuranose 1, 2'; 2, 3' dianhydride with Arthrobacter ureafaciens. 122 19

The sequence of a novel cDNA clone, Aiv-1, for tomato acid invertase was similar to that of TIV1 (Klann et al., 1992) for the enzyme except for a unique intron-like insertion. It is considered that Aiv-1 is derived from either an alternatively spliced mRNA for an isozyme or a pre-mRNA of TIV1.
Jpn J Genet 1992 Dec
PMID:A novel cDNA clone for acid invertase in tomato fruit. 130 71

In certain phages and bacteria, there is a recombination system that specifically promotes the inversion of a DNA fragment. These inversion events appear to act as genetic switches allowing the alternate expression of different sets of genes which in general code for surface proteins. The mechanism of inversion in one class of inversion systems (Gin/Hin) has been studied in detail. It involves the formation of a highly specific nucleoprotein complex in which not only the two recombination sites and the DNA invertase participate but also a recombinational enhancer to which the DNA-bending protein Fis is bound.
Trends Genet 1992 Dec
PMID:DNA inversions in phages and bacteria. 133 27


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>