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)

In vivo jejunal transport of amino acids, monosaccharides, sodium, and electrolytes were studied in rats made nephrotic with puromycin aminonucleoside (PAN) and in pair-fed controls. Studies were performed 14 days after a single intravenous dose of PAN when rats were no longer edematous, but were still hypoproteinemic. There was decreased absorption of glucose, 3-0-methyl glucose, glycine, phenylalanine, histidine, water, and sodium in the nephrotic animals but transport of fructose, lysine and potassium was similar in the nephrotic and control animals. Enzyme kinetic studies for glucose transport showed a mixed type of inhibition affecting both Vm and Km. The jejunal mucosa of nephrotic and control rats had similar ATP content and enzyme activity for lactase, sucrase, maltase and (Na-K)-ATPase and the ratios of RNA to DNA were similar in the nephrotic and control rats. No abnormality of the jejunum was detected by light or electron microscopy. The data suggest that the impairment of absorption is a result of decreased activity of jejunal membrane carrier mechanisms. The altered transport may be secondary to effects related to the metabolic consequences of nephrotic syndrome and does not appear to be related to acute purine aminonucleoside toxicity, edema or malnutrition.
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PMID:Jejunal transport in experimental nephrotic syndrome. 662 9

The effect of vitamin C deficiency on the digestive and absorptive functions of the gut has been investigated in guinea pigs. The absorption of D-glucose was significantly elevated, but that of L-leucine, L-alanine and L-lysine considerably depressed in the intestine of scorbutic guinea pigs compared to controls. The intestinal transport of vitamin B12 was also diminished. Activities of sucrase and alkaline phosphatase on the brush border were enhanced, but that of leucine aminopeptidase markedly reduced in scorbutic animals compared to controls. Maltase activity was unaffected in vitamin C deficient animals. Chemical analysis of the brush borders isolated from scorbutic animals revealed a considerable decrease in membrane protein, total lipids, phospholipids, and free cholesterol contents compared to control animals. In vivo 2-(14)C-acetate incorporation into membrane lipids suggested that the observed decrease in lipid components of the scorbutic membranes is due to reduced synthesis. Administration of ascorbic acid to scorbutic animals ameliorated the intestinal aberrations observed in scurvy.
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PMID:Effect of vitamin C deficiency in guinea pigs on intestinal functions and chemical composition of brush border membrane. 730 86

The Saccharomyces cerevisiae Wbp1 protein is an endoplasmic reticulum (ER), type I transmembrane protein which contains a cytoplasmic dilysine (KKXX) motif. This motif has previously been shown to direct Golgi-to-ER retrieval of type I membrane proteins in mammalian cells (Jackson, M. R., T. Nilsson, and P. A. Peterson. 1993. J. Cell Biol. 121: 317-333). To analyze the role of this motif in yeast, we constructed a SUC2-WBP1 chimera consisting of the coding sequence for the normally secreted glycoprotein invertase fused to the coding sequence of the COOH terminus (including the transmembrane domain and 16-amino acid cytoplasmic tail) of Wbplp. Carbohydrate analysis of the invertase-Wbp1 fusion protein using mannose linkage-specific antiserum demonstrated that the fusion protein was efficiently modified by the early Golgi initial alpha 1,6 mannosyltransferase (Och1p). Subcellular fractionation revealed that > 90% of the alpha 1,6 mannose-modified fusion protein colocalized with the ER (Wbp1p) and not with the Golgi Och1p-containing compartment or other membrane fractions. Amino acid changes within the dily sine motif (KK-->QK, KQ, or QQ) did not change the kinetics of initial alpha 1,6 mannose modification of the fusion protein but did dramatically increase the rate of modification by more distal Golgi (elongating alpha 1,6 and alpha 1,3) mannosyltransferases. These mutant fusion proteins were then delivered directly from a late Golgi compartment to the vacuole, where they were proteolytically cleaved in a PEP4-dependent manner. While amino acids surrounding the dilysine motif played only a minor role in retention ability, mutations that altered the position of the lysines relative to the COOH terminus of the fusion protein also yielded a dramatic defect in ER retention. Collectively, our results indicate that the KKXX motif does not simply retain proteins in the ER but rather directs their rapid retrieval from a novel, Och1p-containing early Golgi compartment. Similar to observations in mammalian cells, it is the presence of two lysine residues at the appropriate COOH-terminal position which represents the most important features of this sorting determinant.
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PMID:Signal-mediated retrieval of a membrane protein from the Golgi to the ER in yeast. 796 50

The enzyme that catalyzed the conversion of human salivary alpha-amylase family A (HSA-A) to family B (HSA-B) was identified. It was partially purified from the precipitate obtained by centrifugation of human saliva at 105,000 x g for 60 min by solubilization with 3[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate and column chromatographies with Sephacryl S-300-HR and hydroxylapatite. The enzyme preparation was practically free from contaminating exoglycosidases and proteases. The enzyme cleaved the N,N'-diacetylchitobiose moiety of the sugar chain of HSA-A, as shown by the isolation of the protein moiety which contained 1 GlcNAc and 1 Fuc residue and the sugar chain (Gal)2(Fuc)1(GlcNAc)2(Man)3(GlcNAc). This enzyme also cleaved the N,N'-diacetylchitobiose moiety of the sugar chain of human transferrin tetraglycopeptide Asn-Tyr-Asn(GlcNAc)2(Man)3(GlcNAc)2(Gal)2-Lys to yield equimolar amounts of peptide Asn-Tyr-Asn(GlcNAc)Lys and sugar chain (Gal)2(GlcNAc)2(Man)3(GlcNAc). The enzyme was identified as an endo-beta-N-acetylglucosaminidase. The enzyme acted on HSA-A with desialylated and defucosylated outer chain moieties of the sugar chains at a similar rate as that of native HSA-A. The enzyme activity was reduced to 13 and 5% using HSA-A with the sugar chains whose outer chain moieties lacked Gal and GlcNAc, respectively, from the nonreducing end. The enzyme also acted on human transferrin, calf fetuin, and asparagine oligosaccharides of transferrin and fetuin. On the other hand, the enzyme did not act on ovalbumin, RNase B, Taka-amylase, yeast invertase, and ovalbumin asparagine oligosaccharides. These results indicate that human salivary endo-beta-N-acetylglucosaminidase is specific for complex type sugar chains and can release the sugar chains from native glycoproteins and glycopeptides regardless of the existence of a Fuc residue on the proximal GlcNAc of the N,N'-diacetylchitobiose core of their sugar chains. The source of the enzyme was epithelial cells peeling from the oral cavity epithelium into saliva. The enzyme was thought to be integrated on the surface of the epithelial cell membrane. This enzyme was named endo-beta-N-acetylglucosaminidase HS. Thus, these studies indicate that the properties of the enzyme are distinct from those of known endo-beta-N-acetylglucosaminidase and endo-beta-N-acetylglucosaminidase HS is a novel endo-beta-N-acetylglucosaminidase.
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PMID:Human salivary endo-beta-N-acetylglucosaminidase HS specific for complex type sugar chains of glycoproteins. 834 Apr 28

To assess the effects of hypothyroidism (HT) on small-intestinal function, HT was induced in rats (120-150 g) by methimazole in drinking water. After 6 wk of methimazole, intestinal absorption studies were performed in HT and in control (C) rats by in situ luminal perfusion of a 20-cm proximal jejunal loop with a bicarbonate buffer containing sodium, glucose or fructose, glycine or lysine, and phenol red as a nonabsorbable marker for determination of water fluxes. Mucosa from the perfused segment was taken for assay of disaccharidases and ATPases and for light and electron microscopy. Compared with C rats, HT rats had significantly lower jejunal transport rates of water (2.54 +/- 0.36 versus 5.02 +/- 0.7 microL/min/microgram mucosal protein, p < 0.03), sodium (37.1 +/- 10.3 versus 102.7 +/- 18.6 mumol/min/microgram protein, p < 0.05), and glucose (1.49 +/- 0.28 versus 5.17 +/- 0.82 mumol/min/microgram protein, p < 0.02). A reduction in glycine transport was also observed but did not attain statistical significance (p = 0.058). Fructose and lysine transport was unchanged. Mucosal sucrase and lactase activities were similar in both groups, but Na,K-ATPase was significantly lower in HT rats (1.17 +/- 0.3 versus 4.03 +/- 1.5 mumol inorganic phosphate/h/mg protein; p < 0.05), with a diminution of ouabain binding sites by 41.5%. Light microscopy of jejunal mucosa from HT rats did not differ from that from C rats; electron microscopy showed mild mitochondrial swelling in HT enterocytes. A group of HT rats were treated with L-thyroxine during 4 wk; these rats had absorption rates, mucosal enzyme activities, ouabain binding, and mucosal morphology not different from C rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of hypothyroidism on jejunal mucosal function: study by in situ luminal perfusion in rats. 839 45

The extent of N-glycosylation of yeast external invertase at each of the 14 potential sites was determined by the combination of proteolytic digestions and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI/TOF-MS). The average molecular mass of the intact external invertase was determined as 97 kDa by MALDI/TOF-MS. The intact protein was digested with trypsin, Lys-C and Asp-N, followed by high-performance liquid chromatographic separation. The proteolytic digests were analyzed by MALDI/MS screening for the glycopeptides. The glycopeptides were then treated with peptide:N-glycosidase F (PNGase F) and/or endo-beta-N-acetylglucosaminidase (Endo H) and the molecular mass of the deglycosylated peptide was determined by MALDI/MS and matched with the peptide predicted by a computer program. The sequences of some peptides or deglycosylated peptides were identified by the MALDI post-source decay technique. The size of the oligosaccharide, the degree of glycosylation and the distribution of the oligosaccharides at each individual potential glycosylation site were characterized. This information goes for beyond previously published data and sometimes differs from them. During this study, the amino acid sequence originally derived from the DNA sequence of the gene coding for invertase was also verified and it was found that this protein when expressed from SUC2 gene might be created as more than one sequence which differ by a few amino acid substitutions (Asn58<-->Thr, Asn65-->His and Val412<-->Ala).
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PMID:Determination of N-linked glycosylation of yeast external invertase by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. 1022 60

To further understand how membrane proteins are sorted in the secretory system, we devised a strategy that involves the expression of a membrane-anchored yeast invertase in transgenic plants. The construct consisted of a signal peptide followed by the coding region of yeast invertase and the transmembrane domain and cytoplasmic tail of calnexin. The substitution of a lysine near the C terminus of calnexin with a glutamic acid residue ensured progression through the secretory system rather than retention in or return to the endoplasmic reticulum. In the transformed plants, invertase activity and a 70-kD cross-reacting protein were found in the vacuoles. This yeast invertase had plant-specific complex glycans, indicating that transport to the vacuole was mediated by the Golgi apparatus. The microsomal fraction contained a membrane-anchored 90-kD cross-reacting polypeptide, but was devoid of invertase activity. Our results indicate that this membrane-anchored protein proceeds in the secretory system beyond the point where soluble proteins are sorted for secretion, and is detached from its membrane anchor either just before or just after delivery to the vacuole.
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PMID:Delivery of a secreted soluble protein to the vacuole via a membrane anchor. 1044 79

Raman optical activity (ROA) spectra have been measured for the proteins hen phosvitin, yeast invertase, bovine alpha-casein, soybean Bowman-Birk protease inhibitor, and rabbit Cd(7)-metallothionein, all of which have irregular folds in the native state. The results show that ROA is able to distinguish between two types of disorder. Specifically, invertase, alpha-casein, the Bowman-Birk inhibitor, and metallothionein appear to possess a "static" type of disorder similar to that in disordered states of poly(L-lysine) and poly(L-glutamic acid); whereas phosvitin appears to possess a more "dynamic" type of disorder similar to that in reduced (unfolded) lysozyme and ribonuclease A and also in molten globule protein states. In the delimiting cases, static disorder corresponds to that found in loops and turns within native proteins with well-defined tertiary folds that contain sequences of residues with fixed but nonrepetitive phi,psi angles; and dynamic disorder corresponds to that envisaged for the model random coil in which there is a distribution of Ramachandran phi,psi angles for each amino acid residue, giving rise to an ensemble of interconverting conformers. In both cases there is a propensity for the phi,psi angles to correspond to the alpha, beta and poly(L-proline) II (PPII) regions of the Ramachandran surface, as in native proteins with well-defined tertiary folds. Our results suggest that, with the exception of invertase and metallothionein, an important conformational element present in the polypeptide and protein states supporting the static type of disorder is that of the PPII helix. Long sequences of relatively unconstrained PPII helix, as in alpha-casein, may impart a plastic (rheomorphic) character to the structure.
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PMID:Solution structure of native proteins with irregular folds from Raman optical activity. 1109 13

Peroral administration of Vilon (Lys-Glu) to male and female Wistar rats aging 3 and 11 months changed activity of digestive enzymes (invertase, maltase, alkaline phosphatase, and amino- and dipeptidases) in various portions of the gastrointestinal tract. The increase in enzyme activity was most pronounced in 11-month-old animals, which diminished differences between rats of various ages. Our results indicate that Vilon produces positive effects on digestive enzyme activity during aging.
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PMID:Effect of the dipeptide vilon on activity of digestive enzyme in rats of various ages. 1158 13

Knowing that human blood monocyte-derived dendritic cells express cell-surface mannose-specific lectins, we prepared various mannoses containing glycoconjugates with the aim of developing highly specific synthetic carriers of oligonucleotides and genes. Conjugates were prepared from oligosaccharides obtained by hydrazinolysis of Saccharomyces cerevisiae invertase glycopeptides. The reducing saccharides were converted into glycosynthons, i.e., into glyco-amino acids. Fluorescein derivatives were obtained by coupling the free carboxyl group of oligosaccharyl-pyroglutamate to the alpha-amino group of epsilon-fluoresceinyl-thiocarbamyl lysine methyl ester. It has been shown by others that glycosylated linear oligolysines containing up to six alpha-D-mannopyranosylphenylthiocarbamyl units have a high affinity for the human mannose receptor. In order to obtain fully biodegradable clusters and to improve both the specificity and the selectivity, disaccharides transformed into glycosynthons were coupled to pentalysine carriers (Lys5-Ala-Cys-NH2). Glycosylated pentalysyl cysteine conjugates were made fluorescent upon substitution of the cysteine thiol group with fluorescein iodoacetamide. As shown by flow cytofluorimetry, both the dimannoside clusters and yeast oligomannosides were very efficiently taken up by DC, conversely lactoside clusters were not.
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PMID:Uptake of dimannoside clusters and oligomannosides by human dendritic cells. 1216 31


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