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)

Saccharomyces cerevisiae Man9-alpha-mannosidase, responsible for trimming Man9GlcNAc2 in the endoplasmic reticulum to Man8GlcNAc2, the substrate for oligosaccharide elongation, has been purified to homogeneity from stabilized microsomal membranes without employing autolytic digestion. The activity was solubilized by the zwitterionic detergent, 3-[(3-cholamidopropyl)dimethyl ammonio]-1-propanesulphonate (CHAPS), whose presence was necessary for maximal activity. Purification included Q-Sepharose ion-exchange chromatography, preparative isoelectric focusing and HPLC gel filtration on TSK 3000 matrix. Overall purification from post-nuclear supernatants was estimated to be 110,000-fold with a 50% recovery of activity. The purified enzyme hydrolysed Man9GlcNAc1,2 from thyroglobulin or oligosaccharide-lipid, but not invertase Man9GlcNAc, Man1 alpha 2Man1 alpha OCH3 or p-nitrophenyl-alpha-D-mannopyranoside. Conversion of thyroglobulin Man9GlcNAc to Man8GlcNAc was linear with time and enzyme concentration, with an apparent Km of 0.2 mM and a specific activity of 220 IU/mg. Glc3Man9GlcNAc2 from oligosaccharide-lipid was as good a substrate as Man9GlcNAc, but the lipid-linked Man7GlcNAc2 isomer was hydrolysed at only 10% of this rate. Hydrolysis of defined isomers of IgM and bovine thyroglobulin Man6,7,8GlcNAc indicated that, for maximal alpha 1,2-mannosidase activity, only the alpha 1,2-linked terminal mannoses on the alpha 3 branch of the Man9GlcNAc precursor were dispensable. Isomers lacking the terminal alpha 1,2-linked mannose on the alpha 6 branch were hydrolysed at only approximately 10% of the maximal rate. The enzyme exhibited a pI of 5.3 and a pH optimum at 6.5. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis in the absence of reducing agents gave a single sharp band at 66 kDa, while in the presence of beta-mercaptoethanol equimolar amounts of two peptides, one of 44 kDa and one of 23 kDa, were obtained. Sizing on Sephacryl SF300, Superose 12 and TSK 3000 provided a holoenzyme mol. wt of 60-68 kDa, indicating that the isolated active form of the Man9-alpha-mannosidase was composed of one each of the sulphydryl-bonded dissimilar peptides. The enzyme bound to concanavalin A (ConA)-Sepharose and was eluted with alpha-methylmannoside, indicating the presence of high-mannose oligosaccharides. The Man9-alpha-mannosidase required low levels of Ca2+, which could be removed by EGTA. Activity was restored by Ca2+ or Zn2+, but not by Mg2+ or Mn2+.
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PMID:Glycoprotein biosynthesis in yeast: purification and characterization of the endoplasmic reticulum Man9 processing alpha-mannosidase. 182 40

Oral administration of embelin (75 mg/kg per day, daily for 15 and 30 days) to male rats caused significant elevation in the uptake of D-glucose, L-alanine, L-leucine and calcium in small intestinal segments. Embelin also produced significant increases in intestinal brush border membrane-associated enzymes (sucrase, lactase, maltase, alkaline phosphatase and leucine aminopeptidase) in both intestinal homogenates and partially purified brush border membrane preparations. Significant increases were also noted for microsomal glucose-6-phosphatase and cytosolic lactate dehydrogenase. Increase in brush border membrane-associated total lipids, phospholipids, cholesterol, triacylglycerol, unesterified fatty acids and ganglioside sialic acid were seen but not in the cholesterol/phospholipid molar ratio. All these changes returned to control or near control levels following withdrawal of the drug.
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PMID:Effects of embelin, a male antifertility agent, on absorptive and digestive functions of rat intestine. 192 15

The endoplasmic reticulum of mammalian cells contains a heat shock protein of approximately 70 kDa (hsp70) termed binding protein BiP that is thought to promote the folding and subunit assembly of newly synthesized proteins. To study BiP function, we placed the BiP-encoding gene from Saccharomyces cerevisiae under the control of a regulated promoter and examined the effects of BiP depletion. Reduction of BiP protein to about 15% of normal levels led to a profound reduction in secretion of alpha factor and invertase. At the same time, unglycosylated precursors of these proteins accumulated intracellularly. The predominant form of the invertase precursor had undergone signal sequence cleavage but accumulated as a soluble species in the cytosol. In contrast, the alpha-factor precursor was exclusively in the signal-uncleaved form. It sedimented with microsomal membranes and was exposed at the cytoplasmic face in a protease-resistant form. These findings suggest that, in yeast, BiP function is required for translocation of soluble proteins into the endoplasmic reticulum at a stage beyond the initial nascent chain-membrane association.
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PMID:Binding protein BiP is required for translocation of secretory proteins into the endoplasmic reticulum in Saccharomyces cerevisiae. 199 57

Protoplasts purified from mesocarp of nonpollinated pea (Pisum sativum L.) ovaries released acid invertase to the incubation medium. The association of the acid invertase with microsomal fractions, and the sensitivity to energy-metabolism inhibitors and to tunicamycin, indicated the secretory nature of the release process. In the presence of GA3 (10 microM), the protoplasts increased their invertase secretion at about 60 min, this effect being counteracted by tunicamycin but not by cycloheximide. Subcellular fractionation of GA3-treated protoplasts showed that higher invertase secretion was the result of a promotion of invertase transfer from endoplasmic reticulum (ER) to Golgi apparatus.
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PMID:Gibberellic acid stimulates acid invertase secretion in pea ovary protoplasts. 200 43

Administration of Embelin, an experimental antifertility agent, to male rats (20 mg/kg body wt/day, daily for 15 and 30 days), caused an elevation in the uptake of D-glucose, L-alanine, L-leucine, and calcium in the small intestinal segments. An increase was also noted in the intestinal brush border membrane (BBM)-associated enzymes, sucrase, lactase, maltase, alkaline phosphatase, and leucine aminopeptidase in both the intestinal homogenates and partially purified BBM preparations, particularly after 30-day administration of the drug. Embelin treatment also caused a significant increase in the microsomal glucose-6-phosphatase and the cytosolic enzyme, lactate dehydrogenase. In the Embelin-treated animals BBM-associated total lipids, phospholipids, cholesterol, triacylglycerol, unesterified fatty acids, ganglioside-sialic acids as well as the cholesterol/phospholipids molar ratio showed a considerable increase. All these changes in the Embelin-treated animals were restored back to the normal or near normal biochemical makeup when the drug therapy was withdrawn and the animals were allowed to recover for another 15 and 30 days, respectively.
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PMID:Changes in glucose/amino acid/calcium uptake and brush-border membrane-associated enzymes in rat small intestine after the administration of embelin (plant benzoquinone), an antifertility agent. 211 47

Some diets exert a considerable influence on porphyrin metabolism and induction of microsomal liver enzymes in experimental porphyria induced by hexachlorobenzene (HCB). As HCB and its metabolites come into direct contact with intestinal mucosa, this study investigated the changes in the activities of intestinal disaccharidases and gamma-glutamyl transferase in a model of HCB-induced porphyria. The effects of different diets on enzymatic activities during HCB intoxication were also studied. HCB was administered by gastric tube at 3.5 mmol/kg body weight daily for 90 and 61 days. HCB intoxication strongly diminished the activities of intestinal lactase, maltase, sucrase, cellobiase and trechalase. Carbohydrate diets (with 78 weight % glucose or starch), given simultaneously with HCB treatment, exerted a protective effect on disaccharidase activities. These regimens maintained cellobiase and trechalase within the normal levels and even increased maltase. High-fat/high-protein diets (with 30% either butter or sunflower oil and 31% casein) aggravated the decrease of all disaccharidases. In contrast with the decrease in disaccharidase activity, intestinal gamma-glutamyl transferase was increased, suggesting multiple mechanisms for the action of HCB intoxication on the intestinal enzyme system. Diet had a pronounced modifying effect.
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PMID:Changes in some intestinal enzyme activities in experimental hexachlorobenzene-induced porphyria and modifying effects of diet. 288 67

The influence of vitamin D and C deficiency on the kinetic parameters of sucrase and alkali phosphatase activities was studied in the microsomal fraction of the small intestinal mucosa of guinea pigs. It was found that Km values for these enzymes did not depend on the animal providing with these vitamins. Deficiency of one of these vitamins did not influence sucrase activity, however, simultaneous elimination of vitamins D and C resulted in the activity rise by 92%. Alkali phosphatase and Ca-ATPase activities proved to be similarly dependent on providing with vitamin D in the presence of vitamin C in the ration, while in the absence of vitamin C this dependence was not observed.
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PMID:[Enzymatic activity of the microsomal fraction of the mucosa of the small intestine in guinea pigs with vitamin D and C deficiencies]. 296 18

The step which requires the hydrolysis of a nucleoside triphosphate for translocation of a protein across microsome was investigated by studying translocation uncoupled from translation using two truncated products of invertase: one product contains the first 262 amino acids of the secreted invertase (Inv262); the other, the first 104 amino acids (Inv104). The truncated products were translated from RNA transcripts without a stop codon. It is demonstrated that the translated products contain an associated ribosome, and the associated ribosome is essential for the posttranslational translocation phenomenon. Also, it is demonstrated that binding of Inv262 to microsomal vesicles made from the cell wall-less mutant of Neurospora crassa does not require the hydrolysis, or the presence, of a nucleoside triphosphate. However, the posttranslational translocation across the membrane, as monitored by glycosylation of the translocated polypeptide chain, does. The data suggest that a nucleoside triphosphatase activity is associated with the translocation of invertase across the membrane. Furthermore, it is demonstrated that binding, and subsequent translocation across the membrane, is dependent on trypsin-sensitive membrane component(s).
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PMID:Translocation of a fragment of invertase across microsomal vesicles isolated from Neurospora crassa requires the hydrolysis of a nucleoside triphosphate. 297 55

Gastric and intestinal phenotypic expression in 37 surgically obtained primary signet ring cell carcinomas, five of their metastases to lymph nodes, and three signet ring cell carcinomas transplanted into nude mice were determined by biochemical, mucin, histochemical, and ultrastructural studies. Crude extracts of cancer tissues were used for measurements of pepsinogen isozymes, sucrase, aminopeptidase (microsomal), and alkaline phosphatase. Histochemical staining of mucin by paradoxical concanavalin A, the galactose oxidase-Schiff sequence and sialidase-galactose oxidase-Schiff, and the periodate-borohydride technique/potassium hydroxide/periodic acid-Schiff procedure was performed. The procedures allowed clear definition of pyloric gland, surface mucous, small and large intestinal goblet, and intestinal absorptive cell types. Of 40 specimens examined, 19 consisted entirely of gastric-type cells, and three entirely of intestinal-type cells. The others consisted of mixtures of gastric and intestinal-type cells. The observed high incidence of intestinal-type cells in signet ring cell carcinomas suggested that intestinal-type cells develop independently from intestinal metaplasia within signet ring cell carcinomas (diffuse-type gastric cancers), which probably originate from nonmetaplastic gastric mucosa.
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PMID:Gastric and intestinal phenotypic expressions of human signet ring cell carcinomas revealed by their biochemistry, mucin histochemistry, and ultrastructure. 301

We have determined that prepro-carboxypeptidase Y and a truncated form of pre-invertase can be translocated across the yeast microsomal membrane post-translationally in a homologous in vitro system. The yeast secretory protein prepro-alpha-factor which was previously shown to be an efficient posttranslational translocation substrate is therefore not unique in this regard, but rather the yeast ER protein translocation machinery is generally capable of accepting substrates from a ribosome-free, soluble pool. However, within our detection limits, full-length pre-invertase could not be translocated posttranslationally, but was translocated co-translationally. This indicates that not every fully synthesized pre-protein can use this pathway, presumably because normal or aberrant folding characteristics can interfere with translocation competence.
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PMID:Prepro-carboxypeptidase Y and a truncated form of pre-invertase, but not full-length pre-invertase, can be posttranslationally translocated across microsomal vesicle membranes from Saccharomyces cerevisiae. 328 44


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