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 NCYC 366 is susceptible to cold osmotic shock. Exponentially growing cells from batch cultures grown in defined medium at 30 C, after being suspended in 0.8 m mannitol containing 10 mm ethylenedia-minetetraacetic acid and then resuspended in ice-cold 0.5 mm MgCl(2), accumulated the nonmetabolizable solutes d-glucosamine-hydrochloride and 2-aminoisobutyrate at slower rates than unshocked cells; shocked cells retained their viability. Storage of unshocked batch-grown cells in buffer at 10 C led to an increase in ability to accumulate glucosamine, and further experiments were confined to cells grown in a chemostat under conditions of glucose limitation, thereby obviating the need for storing cells before use. A study was made of the effect of the different stages in the cold osmotic shock procedure, including the osmotic stress, the chelating agent, and the cold Mg(2+)-containing diluent, on viability and solute-accumulating ability. Growth of shocked cells in defined medium resembled that of unshocked cells; however, in malt extract-yeast extract-glucose-peptone medium, the shocked cells had a longer lag phase of growth and initially grew at a slower rate. Cold osmotic shock caused the release of low-molecular-weight compounds and about 6 to 8% of the cell protein. Neither the cell envelope enzymes, invertase, acid phosphatase and l-leucine-beta-naphthylamidase, nor the cytoplasmic enzyme, alkaline phosphatase, were released when yeast cells were subjected to cold osmotic shock.
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PMID:Cold osmotic shock in Saccharomyces cerevisiae. 500 Dec 1

Mutant strains of Neurospora crassa that lack trehalase and are unable to grow on trehalose were isolated, and the gene (tre) was positioned on the right arm of linkage group I. Maltase and beta-galactosidase activities are almost identical in tre(-) strains, whereas that of invertase was reduced by more than half and those of acid phosphatase and amylase were somewhat increased. Heterocaryons between standard and trehalaseless strains yield less than one-tenth the activity of the former. In addition, strains with duplications heterozygous for trehalase produce less than 1% of the activity of the standard strain. An inhibitor of trehalase has been found in tre(-) strains; its sensitivity to heat and proteolysis, and its nondialyzability suggest that this substance is a protein. The mig gene, which determines the rate of migration of trehalase on acrylamide gels, has been shown to be less than 1 map unit away from the tre gene.
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PMID:Isolation, mapping, and characterization of trehalaseless mutants of Neurospora crassa. 500 Dec 11

The synthesis of the glycoprotein enzymes, invertase and acid phosphatase, by protoplasts of Saccharomyces mutant 1016, is inhibited by 2-deoxy-d-glucose (2-dG) after a 20- to 30-min lag period under conditions (external sugar to 2-dG ratio of 40:1) which cause only a slight decrease in total protein synthesis. Formation of one intracellular enzyme, alpha-glucosidase, is also sensitive, but production of another, alkaline phosphatase, is unaffected. A nonmetabolized glucose analogue, 6-deoxy-d-glucose, had no inhibitory effect. The total uptake of external fructose and maltose was decreased by 2-dG after a lag period of about the same duration as that before the inhibition of synthesis of enzymes or of mannan and glucan; during this time 2-dG was taken up by the protoplasts and accumulated primarily as 2-dG-6-phosphate (2-dG-6-P). Studies in vitro showed that 2-dG-6-P inhibits both yeast phosphoglucose isomerase and phosphomannose isomerase. The intracellular levels of the 6-phosphates of glucose, fructose, and mannose did not increase in the presence of 2-dG. We suggest that the high internal level of 2-dG-6-P blocks synthesis of the cell wall polysaccharides and glycoproteins in two ways. It directly inhibits the conversion of fructose-6-P to glucose-6-P and to mannose-6-P. At the same time, it restricts the transport of fructose and maltose into the cell; however, the continuing limited uptake of the sugars still provides sufficient energy for protein synthesis. The cessation of alpha-glucosidase synthesis is probably a result of depletion of the internal pool of maltose (the inducer). Our findings support the suggestion that restriction of synthesis of the carbohydrate moiety of glycoproteins reduces formation of the active enzyme.
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PMID:Inhibition by 2-deoxy-D-glucose of synthesis of glycoprotein enzymes by protoplasts of Saccharomyces: relation to inhibition of sugar uptake and metabolism. 505 66

The exposure of cultivated mouse macrophages to sucrose (0.009-0.03 M) leads to the formation of large phase- and electron-lucent, acid phosphatase-positive vacuoles in the perinuclear region. The vacuolization process and the uptake of sucrose-(14)C is blocked by inhibitors of pinocytosis and stimulated by calf serum in the medium. These results suggest the uptake of sucrose by pinocytosis and its subsequent segregation and storage in secondary lysosomes. The addition of sucrose also increases the total content of three macrophage lysosomal hydrolases. The addition of invertase to the environment of sucrose-laden macrophages leads to the prompt shrinkage of the sucrose-containing lysosomes. This is accompanied by the intracellular hydrolysis of sucrose to fructose and glucose residues which are promptly excreted into the medium. The uptake of invertase, as indicated by the shrinkage of sucrose-containing vacuoles, is blocked by inhibitors of pinocytosis. No effect was noted when invertase was added to macrophages laden with Ficoll, a polysucrose which is not hydrolyzed by the enzyme. The influence of other carbohydrates was then investigated. Monosaccharides with molecular weights up to 220 did not produce vacuolization. However, a certain number of di-, tri-, and tetrasaccharides produced vacuolization identical with that of sucrose. Each of the disaccharides which produced vacuolization was resistant to the complement of macrophage hexosidases, whereas those that were ineffective were degraded by either macrophage or serum enzymes. The addition of beta-glucosidase to cellobiose-laden macrophages resulted in the shrinkage of vacuoles but did not alter the vacuoles of sucrose containing cells. The ability of small, neutral carbohydrates to produce lysosomal swelling is dependent upon both molecular weight and their resistance to lysosomal hydrolases.
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PMID:The uptake, storage, and intracellular hydrolysis of carbohydrates by macrophages. 578 68

Brock, Thomas D. (Indiana University, Bloomington). Biochemical and cellular changes occurring during conjugation in Hansenula wingei. J. Bacteriol. 90:1019-1025. 1954.-A technique has been devised for deagglutinating mixed populations of conjugating cells so as to be able to visualize microscopically early stages of the conjugation process. A cell can form a conjugation tube only when in contact with a cell of opposite mating type, but may do so even if the mate is unresponsive or ultraviolet-inactivated. Cell fusion occurs, however, only when both cells are able to form conjugation tubes in a region of contact. Fusion begins almost as soon as the two cells begin to form protuberances, and long before any dissolution of cell-wall material between the cells occurs. A cell which has conjugated in one region of its cell wall is still able to conjugate with another cell in another region, so that triply and quadruply conjugated cells are occasionally formed. There is no significant net increase in deoxyribonucleic acid, ribonucleic acid, protein, or carbohydrate which might be related to the conjugation process, because any minor changes that occur in these components are also detected when cells of only one mating type are incubated or when the conjugation process is inhibited with the antibiotic cycloheximide. Changes in activity of beta-1,3-glucanase (with laminarin as substrate) and beta-1,6-glucanase (with pustulan as substrate) have been measured during the conjugation process, in addition to changes in the activity of several control enzymes which would not be expected to be related to the conjugation process. Significant increases in invertase (sucrase), laminarinase, and pustulanase were detected, and minimal increases occurred in beta-glucosidase and acid phosphatase. However, these same increases were also observed in controls involving only one mating type; thus, these increases are probably not related to the conjugation process, but may be a result of other processes which probably occur during incubation in the conjugation medium.
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PMID:Biochemical and cellular changes occuring during conjugation in Hansenula wingei. 584 91

1. Growth of a biotin-requiring strain of Saccharomyces cerevisiae in a medium containing a suboptimum concentration of biotin for growth caused a decreased synthesis of ornithine carbamoyltransferase as compared with yeast grown in a medium containing an optimum concentration of biotin. Inclusion of the biotin homologues norbiotin or homobiotin, but not bishomobiotin, in the biotin-deficient medium caused an appreciable increase in ornithine carbamoyltransferase synthesis without affecting growth or synthesis of total RNA and protein. The addition of norbiotin to biotin-deficient medium had no effect on the respiratory activity of the yeast or on the synthesis of aspartate carbamoyltransferase, acid phosphatase, beta-fructofuranosidase or malate dehydrogenase. 2. Synthesis of acetylornithine deacetylase and acetylornithine acetyltransferase was slightly diminished by the imposition of biotin deficiency, but the effect was not as great as on ornithine carbamoyltransferase synthesis. Incorporation of norbiotin in the biotin-deficient medium had no marked effect on the synthesis of any other arginine-pathway enzyme except ornithine carbamoyltransferase. 3. l-Ornithine induced synthesis of ornithine carbamoyltransferase in yeast grown in biotin-deficient medium, but in yeast grown in this medium supplemented with norbiotin it repressed synthesis of the enzyme. l-Arginine had no detectable effect on ornithine carbamoyltransferase synthesis by the yeast grown in biotin-deficient medium with or without norbiotin. l-Aspartate repressed synthesis of ornithine carbamoyltransferase in biotin-deficient yeast and completely nullified the stimulatory effect of norbiotin on synthesis of the enzyme in this yeast. 4. There was no increase in ornithine carbamoyltransferase synthesis in biotin-deficient yeast incubated in phosphate buffer, pH4.5, containing glucose and biotin or norbiotin. In biotin-deficient yeast suspended in complete medium containing an optimum concentration of biotin, there was an increase in ornithine carbamoyltransferase synthesis only after the onset of growth.
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PMID:A specific requirement for biotin in the synthesis of ornithine carbamoyltransferase by yeast. 596 54

One of the cyr 1 mutants (cyr 1-2) in yeast produced low levels of adenylate cyclase and cyclic AMP at 25 degrees and was unable to derepress acid phosphatase. Addition of cyclic AMP to the cyr1-2 cultures elevated the level of repressible acid phosphatase activity. The bcy1 mutation, which suppresses the cyr1-2 mutation by allowing activity of a cyclic AMP-independent protein kinase, also allows acid phosphatase synthesis without restoring adenylate cyclase activity. The CYR3 mutant had structurally altered cyclic AMP-dependent protein kinase and was unable to derepress acid phosphatase. The cyr1 locus was different from pho2, pho4 and pho81, which were known to regulate acid phosphatase synthesis. Mutants carrying cyr1-2 and pho80, PHO81c, PHO82 or pho85 mutations, which confer constitutive synthesis of repressible acid phosphatase, produced acid phosphatase. The cyr1-2 mutant produced significantly low levels of invertase and alpha-D-glucosidase. These results indicated that cyclic AMP-dependent protein kinase exerts its function in the synthesis of repressible acid phosphatase and other enzymes.
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PMID:Regulation of repressible acid phosphatase by cyclic AMP in Saccharomyces cerevisiae. 609 Feb 71

The activity of the marker enzymes lactase, sucrase, neutral alpha-glucosidase, alkaline phosphatase, gamma-glutamyl transferase, leucyl-beta-naphthylamidase (brush border); 5-nucleotidase (basolateral membrane); and acid phosphatase and N-acetyl-beta-glucosaminidase (lysosomes) in jejunal biopsies from patients with the stagnant-loop syndrome and controls was studied. The activity of gamma-glutamyl transferase was increased in the patient group; the activity of the other enzymes did not differ significantly in patients and controls. The DNA to protein ratio was increased in the patient group. The results do not support the hypothesis of epithelial damage in the human stagnant-loop syndrome.
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PMID:Enzymatic activities in jejunal biopsy specimens from patients with the stagnant-loop syndrome. 614 77

The transport of newly synthesized proteins to the yeast cell surface has been analyzed by a modification of the technique developed by Kaplan et al. (Kaplan, G., C. Unkeless, and Z.A. Cohn, 1979, Proc. Natl. Acad. Sci. USA, 76:3824-3828). Cells metabolically labeled with (35)SO(4)(2-) are treated with trinitrobenzenesulfonic acid (TNBS) at 0 degrees C under conditions where cell-surface proteins are tagged with trinitrophenol (TNP) but cytoplasmic proteins are not. After fractionation of cells into cell wall, membrane and cytoplasmic samples, and solubilization with SDS, the tagged proteins are immunoprecipitated with anti-TNP antibody and fixed staphylococcus aureus cells. Analysis of the precipitates by SDS gel electrophoresis and fluorography reveals four major protein species in the cell wall (S(1)-S(4)), seven species in the membrane fraction (M(1)-M(7)), and no tagged proteins in the cytoplasmic fraction. Temperature-sensitive mutants defective in secretion of invertase and acid phosphatase (sec mutants; Novick, P., C. Field, and R. Schekman, 1980, Cell, 21:204-215) are also defective in transport of the 11 major cell surface proteins at the nonpermissive temperature (37 degrees C). Export of accumulated proteins is restored in an energy- dependent fashion when secl cells are returned to a permissive temperature (24 degrees C). In wild-type cells the transit time for different surface proteins varies from less than 8 min to about 30 min. The asynchrony is developed at an early stage in the secretory pathway. All of the major cell wall proteins and many of the externally exposed plasma membrane proteins bind to concanavalin A. Inhibition of asparagine-linked glycosylation with tunicamycin does not prevent transport of several surface proteins.
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PMID:Export of major cell surface proteins is blocked in yeast secretory mutants. 633 19

Yeast cells secrete a variety of glycosylated proteins. At least two of these proteins, invertase and acid phosphatase, fail to be secreted in a new class of mutants that are temperature-sensitive for growth. Unlike the yeast secretory mutants previously described (class A sec mutants; Novick, P., C. Field, and R. Schekman, 1980, Cell., 21:205-420), class B sec mutants (sec 53, sec 59) fail to produce active secretory enzymes at the restrictive temperature (37 degrees C). sec 53 and sec 59 appear to be defective in reactions associated with the endoplasmic reticulum. Although protein synthesis continues at a nearly normal rate for 2 h at 37 degrees C, incorporation of [3H]mannose into glycoprotein is reduced. Immunoreactive polypeptide forms of invertase accumulate within the cell which have mobilities on SDS PAGE consistent with incomplete glycosylation: sec 53 produces little or no glycosylated invertase, and sec 59 accumulates forms containing 0-3 of the 9-10 N-linked oligosaccharide chains that are normally added to the protein. In addition to secreted enzymes, maturation of the vacuolar glycoprotein carboxypeptidase Y, incorporation of the plasma membrane sulfate permease activity, and secretion of the major cell wall proteins are blocked at 37 degrees C.
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PMID:Yeast secretory mutants that block the formation of active cell surface enzymes. 636 71


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