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

---

Query: EC:3.2.1.26 (invertase)
4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A recessive mutant cat1-1, wild type CAT1, was isolated in Saccharomyces cerevisiae. It did not grow on glycerol nor ferment maltose even with fully constitutive, glucose resistant maltase synthesis. It prevented derepression of isocitrate lyase, fructose-1,6-diphosphatase and maltase in a constitutive but glucose sensitive maltase mutant. Derepression of malate dehydrogenase was retarded and slowed down. Sucrose fermentation and invertase synthesis was not affected. Respiration was normal. From this mutant, two reverse mutants were isolated. One was recessive, acted as a suppressor of cat1-1 and was called cat2-1, wild type CAT2; the other was dominant and allelic to CAT1 and designated CAT1-2d and cat2-1 caused an earlier derepression of enzymes studied but did not affect the repressed nor the fully derepressed enzyme levels. CAT1-2d and cat2-1 did not show any additive effects. It is proposed that carbon catabolite repression acts in two ways. The direct way represses synthesis of sensitive enzymes, during growth on repressing carbon sources whereas the other way regulates the derepression process. After alleviation of carbon catabolite repression, gene CAT1 becomes active and prevents the activity of CAT2 which functions as a repressor of sensitive enzyme synthesis. The CAT2 gene product has to be eliminated before derepression can actually occur. The time required for this causes a delay in derepression after the depletion of a repressible carbon source. cat1-1 cannot block CAT2 activity and therefore, derepression is blocked. cat2-1 is inactive and derepression can start after carbon catabolite repression has ceased. CAT1-2d permanently active as a repressor of CAT2 and eliminates the delay in derepression.
...
PMID:Genetics of carbon catabolite repression in Saccharomycess cerevisiae: genes involved in the derepression process. 19 40

A new technique has been developed for the isolation of membrane vesicles from the vitamin D-deficient and vitamin D-treated chick intestinal brush border membrane. The technique involves removal of nuclei from a low speed pellet by discontinuous sucrose gradient centrifugation. The resulting intact brush borders are then homogenized in 0.5 M Tris and the membrane fragments purified on a glycerol gradient. This preparation represents a 20-fold purification of the brush border marker sucrase. After 1alpha-hydroxyvitamin D3 treatment there is a significant increase in membrane phospholipid phosphorous, an alteration in the fatty acid composition of the phosphatidylcholine fraction of membrane phospholipid, and a decrease in sucrase specific activity.
...
PMID:Purification and characterization of chick intestine brush border membrane. Effects of 1alpha(OH) vitamin D3 treatment. 67 42

Rates of glucose uptake in baker's yeast and in the osmophilic yeasts D. hansenii and S. rouxii were investigated at different values of water activity of the milieu, as regulated either by glycerol or sodium chloride. In both cases, D. hansenii could maintain relatively higher rates of glucose uptake. At lower values of water activity, sodium chloride exerted an inhibitory effect on rates of glucose uptake by S. rouxii, while in the presence of glycerol, rates of glucose uptake shown by S. rouxii resembled those shown by D. hansenii. Rates of glucose uptake by baker's yeast were drastically affected at lower values of water activity in the presence of either solute. Lower values of water activity exerted a stimulatory effect on catalase activity of both S. rouxii and D. hansenii. However, activities of baker's yeast with regard to catalase and invertase were moderately affected under such conditions. Results presented may lead to the presumption that osmophilic yeasts, at least partly, have solved the problem of osmotic tolerance over nonosmotolerant strains by possessing a high capacity for maintaining higher rates of glucose uptake, in spite of the adverse external concentration of solute.
...
PMID:The effect of the water activity of the milieu on rates of glucose uptake by the osmophilic yeasts Saccharomyces rouxii and Debaryomyces hansenii. 74 15

Fusarium oxysporum produced maximum extracellular inulinase after 9 days of its growth at 25 degrees C on a medium (pH 5.5) containing 3% fructan and 0.2% sodium nitrate. The level of this enzyme decreased on the addition of either glucose, fructose, galactose or sucrose to F. oxysporum already growing on a fructan-containing medium. A significant increase in invertase production which resulted in an increase of the invertase/inulinase (S/I) ratio, was observed on addition of inulin to this fungus growing on other carbon sources. Glycerol (10%) gave better protection to inulinase against thermal denaturation at 50 degrees C compared to ethylene glycol and sorbitol. Inulinase immobilised in polyacrylamide gel retained 45% of its original activity. The immobilised enzyme showed a higher optimum temperature (45 degrees C) compared to free enzyme (37 degrees C). The immobilised enzyme after storage at 25 degrees C for 96 h showed 58% activity. Thermal stability of entrapped inulinase increased in the presence of inulin.
...
PMID:Production, thermal stability and immobilisation of inulinase from Fusarium oxysporum. 136 87

Phytomonas sp. isolated from Euphorbia characias was adapted to SDM-79 medium. Cells isolated in the early stationary phase of growth were analyzed for their capacity to utilize plant carbohydrates for their energy requirements. The cellulose-degrading enzymes amylase, amylomaltase, invertase, carboxymethylcellulase, and the pectin-degrading enzymes polygalacturonase and oligo-D-galactosiduronate lyase were present in Phytomonas sp. and were all, except for amylomaltase, excreted into the external medium. Glucose, fructose and mannose served as the major energy substrates. Catabolism of carbohydrates occurred mainly via aerobic glycolysis according to the Embden-Meyerhof pathway, of which all the enzymes were detected. Likewise, the end-products of glycolysis, acetate and pyruvate, glycerol, succinate and ethanol were detected in the culture medium, as were the enzymes responsible for their production. Mitochondria were incapable of oxidizing succinate, 2-oxoglutarate, pyruvate, malate and proline, but had a high capacity to oxidize glycerol 3-phosphate. This oxidation was completely inhibited by salicylhydroxamic acid. No cytochromes could be detected either in intact mitochondria or in sub-mitochondrial particles. Mitochondrial respiration was not inhibited by antimycin, azide or cyanide. The glycolytic enzymes, from hexokinase to phosphoglycerate kinase, and the enzymes glycerol kinase, glycerol-3-phosphate dehydrogenase, phosphoenolpyruvate carboxykinase, malate dehydrogenase and adenylate kinase, were all associated with glycosomes that had a buoyant density of about 1.24 g cm-1 in sucrose. Cytochemical staining revealed the presence of catalase in these organelles. The cytosolic enzyme pyruvate kinase was activated by fructose 2,6-bisphosphate, typical of all other pyruvate kinases from Kinetoplastida. The energy metabolism of the plant parasite Phytomonas sp. isolated from E. characias resembled that of the bloodstream form of the mammalian parasite Trypanosoma brucei.
...
PMID:Characterization of carbohydrate metabolism and demonstration of glycosomes in a Phytomonas sp. isolated from Euphorbia characias. 143 59

When nuclear localization sequences (termed NLS) are placed at the N terminus of cytochrome c1, a mitochondrial inner membrane protein, the resulting hybrid proteins do not assemble into mitochondria when synthesized in the yeast Saccharomyces cerevisiae. Cells lacking mitochondrial cytochrome c1, but expressing the hybrid NLS-cytochrome c1 proteins, are unable to grow on glycerol since the hybrid proteins are associated primarily with the nucleus. A similar hybrid protein with a mutant NLS is transported to and assembled into the mitochondria. To identify proteins that might be involved in recognition of nuclear localization signals, we isolated conditional-lethal mutants (npl, for nuclear protein localization) that missorted NLS-cytochrome c1 to the mitochondria, allowing growth on glycerol. The gene corresponding to one complementation group (NPL1) encodes a protein with homology to DnaJ, an Escherichia coli heat shock protein. npl1-1 is allelic to sec63, a gene that affects transit of nascent secretory proteins across the endoplasmic reticulum. Rothblatt, J. A., R. J. Deshaies, S. L. Sanders, G. Daum, and R. Schekman. 1989. J. Cell Biol. 109:2641-2652. The npl1 mutants reported here also weakly affect translocation of preprocarboxypeptidaseY across the ER membrane. A normally nuclear hybrid protein containing a NLS fused to invertase and a nucleolar protein are not localized to the nucleus in npl1/sec63 cells at the nonpermissive temperature. Thus, NPL1/SEC63 may act at a very early common step in localization of proteins to the nucleus and the ER. Alternatively, by affecting ER and nuclear envelope assembly, npl1 may indirectly alter assembly of proteins into the nucleus.
...
PMID:A yeast gene important for protein assembly into the endoplasmic reticulum and the nucleus has homology to DnaJ, an Escherichia coli heat shock protein. 255 4

A mutant strain of Neurospora crassa has been isolated which is derepressed for amylase and beta-fructofuranosidase (invertase). Large amounts of the two enzymes were secreted into the culture medium upon depletion of exogenous carbon source. The resulting increases of the two extracellular enzymes were prevented by actinomycin D, cycloheximide, and glycerol. The starving cells of the mutant strain produced amylase and invertase de novo, as evidenced by incorporation of radioactive amino acids into the enzymes. Preliminary genetic studies indicate that these elevated enzyme levels described are due to a single gene mutation.
...
PMID:Neurospora mutant exhibiting hyperproduction of amylase and invertase. 577 10

Mutants of Saccharomyces cerevisiae with defects in sucrose or raffinose fermentation were isolated. In addition to mutations in the SUC2 structural gene for invertase, we recovered 18 recessive mutations that affected the regulation of invertase synthesis by glucose repression. These mutations included five new snf1 (sucrose nonfermenting) alleles and also defined five new complementation groups, designated snf2, snf3, snf4, snf5, and snf6. The snf2, snf4, and snf5 mutants produced little or no secreted invertase under derepressing conditions and were pleiotropically defective in galactose and glycerol utilization, which are both regulated by glucose repression. The snf6 mutant produced low levels of secreted invertase under derepressing conditions, and no pleiotropy was detected. The snf3 mutants derepressed secreted invertase to 10-35% the wild-type level but grew less well on sucrose than expected from their invertase activity; in addition, snf3 mutants synthesized some invertase under glucose-repressing conditions.--We examined the interactions between the different snf mutations and ssn6, a mutation causing constitutive (glucose-insensitive) high-level invertase synthesis that was previously isolated as a suppressor of snf1. The ssn6 mutation completely suppressed the defects in derepression of invertase conferred by snf1, snf3, snf4 and snf6, and each double mutant showed the constitutivity for invertase typical of ssn6 single mutants. In contrast, snf2 ssn6 and snf5 ssn6 strains produced only moderate levels of invertase under derepressing conditions and very low levels under repressing conditions. These findings suggest roles for the SNF1 through SNF6 and SSN6 genes in the regulation of SUC2 gene expression by glucose repression.
...
PMID:Genes affecting the regulation of SUC2 gene expression by glucose repression in Saccharomyces cerevisiae. 639 17

The enzyme levanase encoded by the sacC gene from Bacillus subtilis was overexpressed in Escherichia coli with the strong, inducible tac promoter. The enzyme was purified from crude E. coli cell lysates by salting out with ammonium sulfate and chromatography on DEAE-Sepharose CL-6B, S-Sepharose, and MonoQ-Sepharose. The purified protein had an apparent molecular mass of 75,000 Da in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which is in agreement with that expected from the nucleotide sequence. Levanase was active on levan, inulin, and sucrose with Km values of 1.2 microM, 6.8 mM, and 65 mM, respectively. The pH optimum of the enzyme acting on inulin was 5.5, and the temperature optimum was 55 degrees C. Levanase was rapidly inactivated at 60 degrees C, but activity could be retained for longer times by adding fructose or glycerol. The enzyme activity was completely inactivated by Ag+ and Hg2+ ions, indicating that a sulfhydryl group is involved. A ratio of sucrase to inulinase activity of 1.2 was found for the purified enzyme with substrate concentrations of 50 mg/ml. The mechanism of enzyme action was investigated. No liberation of fructo-oligomers from inulin and levan could be observed by thin-layer chromatography and size exclusion chromatography-low-angle laser light scattering-interferometric differential refractive index techniques. This indicates that levanase is an exoenzyme acting by the single-chain mode.
...
PMID:Purification and characterization of the Bacillus subtilis levanase produced in Escherichia coli. 764 30

Micro-organisms have developed systems to adapt to sudden changes in the environment. Here we describe the response of the yeast Saccharomyces cerevisiae to osmotic stress. A drop in the water activity (aw) of the medium following the addition of NaCl led to an immediate shrinkage of the cells. During the 2 h following the osmotic shock the cells partially restored their cell volume. This process depended on active protein synthesis. During the recovery period the cells accumulated glycerol intracellularly as a compatible solute and very little glycerol was leaking out of the cell. We have investigated in more detail the enzymes of glycerol metabolism and found that only the cytoplasmic glycerol-3-phosphate dehydrogenase was strongly induced. The level of induction was dependent on the yeast strain used and the degree of osmotic stress. The synthesis of cytoplasmic glycerol-3-phosphate dehydrogenase is also regulated by glucose repression. Using mutants defective in glucose repression (hxk2 delta), or derepression (snf1 delta), and with invertase as a marker enzyme, we show that glucose repression and the osmotic-stress response system regulate glycerol-3-phosphate dehydrogenase synthesis independently. We infer that specific control mechanisms sense the osmotic situation of the cell and induce responses such as the production and retention of glycerol.
...
PMID:Characterization of the osmotic-stress response in Saccharomyces cerevisiae: osmotic stress and glucose repression regulate glycerol-3-phosphate dehydrogenase independently. 808 59


1 2 3 4 Next >>

---