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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)

1. The effects on Neurospora crassa invertase (beta-D-fructofuranoside fructohydrolase, EC 3.2.1.26) of a variety of group specific reagnets and other potential inhibitors were determined during a search for an irreversible inhibitor of the enzyme. Aniline, pyridoxal, enzyme substrate and products did not inactivate invertase under reducing conditions. Bromoacetic acid, iodoacetic acid, iodoacetamide, p-chloromercuribenzoate, hydroxylamine and 2-hydroxy-5-nitrobenzyl bromide were also ineffective. Iodine was the only reagent which irreversibly inhibited invertase. 2. Invertase was rapidly inactivated by low concentrations of iodine, indicating specific inhibition. However, the enzyme could not be protected from this inactivation by substrate. It was not reactivated by mercaptoethanol or cysteine. 3. Experiments on the uptake of radioactive iodine demonstrated that invertase is not iodinated under the conditions of iodine inactivation. 4. The sedimentation (S20,w) value of invertase was not altered by iodine inactivation. One-dimensional electrophoresis and finger-printing of tryptic digests revealed no differences between iodine treated and untreated invertase. There was no loss of carbohydrate from this glycoprotein during iodine inactivation. 5. Standard amino acid analyses of iodine-inactivated invertase showed some loss of tyrosine and a trace amount of methionine sulfone. Attempts to demonstrate oxidation of methionine to the sulfone, through modification of the procedure for preparation of samples for analysis, were unsuccessful. However, oxidation of half-cystine was indicated and further loss of tyrosine noted. A hypothesis is advanced that half-cystine is oxidized by iodine to a normally unstable oxidation state which is maintained and protected by its protein invironment and that loss of tyrosine may be an artifact caused by the presence of this residue during acid hydrolysis.
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PMID:Neurospora crassa invertase. A study of amino acids at the active center. 23 50

A wild type strain of E. coli which produced an invertase capable of hydrolysing sucrose and raffinose transmitted this ability at high frequency to a recipient strain. E. coli C. The ability to ferment both sucrose and raffinose was lost both in the wild type parent and recombinant strains by treatment with ethidium bromide.
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PMID:Transfer of invertase production from a wild strain of Escherichia coli. 32 26

The interaction of alpha-chymotrypsin, invertase, alcohol dehydrogenase and alkaline phosphatase with some ionic and non-ionic surfactants, viz. sodium dodecyl sulphate, dioctyl sodium sulphosuccinate, hexadecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide and Triton X-100, has been examined by studying the effect of varying surfactant concentrations on enzyme activities as well as by determining the time-dependent inactivation and the time-independent inhibition. The kinetic parameters, Km and Vmax, for alpha-chymotrypsin-catalysed reaction in presence of sodium dodecyl sulphate were evaluated. Anionic surfactants markedly decreased enzyme activity, whereas cationic surfactants were less effective. Nonionics showed no effect. This change in enzyme activity was also dependent on the nature of enzyme.
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PMID:Stability and kinetic behaviour of some enzymes in surfactant environment. 263 63

A respiratory deficient mutant of Kluyveromyces fragilis was isolated using ethidium bromide mutagenesis. It was characterized by a loss of cytochromes a + a3 and deficiency in cytochrome b. This petite mutant has brought about modifications in the excretion pattern of beta-fructosidase active on saccharose and inulin. The mutant practically no longer excretes the enzyme, and is incapable of growth and fermentation in the presence of inulin. The study of the activities of different enzyme extracts (culture medium, whole and disrupted cells) on inulin and saccharose suggests the existence of an unique enzyme system capable of taking several forms, and also shows the influence of the growth substrate on the I/S activity ratio.
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PMID:Impairment of insulin assimilation and beta-fructosidase activity due to a petite mutation in Kluyveromyces marxianus. 339 9

It has been shown by genetic analysis that the external and internal invertases from Saccharomyces cerevisiae share a common structural gene [Taussig, R., & Carlson, M. (1983) Nucleic Acids Res. 11, 1943-1954]. However, the only amino acid composition of these two forms of invertase reported to date has revealed extensive differences [Gascon, S., Neumann, N.P., & Lampen, J.O. (1968) J. Biol. Chem. 243, 1573-1577]. We have found from amino acid analyses of both enzymes and sodium dodecyl sulfate-polyacrylamide gel analysis of their cyanogen bromide peptides that they are most likely identical in their amino acid sequence. However, the invertases exhibit dramatically different physical properties, particularly in their stability. The most striking difference was in their renaturation following guanidine treatment where it was shown that inactivated external invertase could be renatured completely. Endo-beta-N-acetylglucosaminidase H treated external invertase was restored to 40% of its original activity while internal invertase remained completely inactive. The observed differences may be attributed to the presence and absence of the oligosaccharide moiety in the external and internal invertases, respectively.
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PMID:Diverse properties of external and internal forms of yeast invertase derived from the same gene. 391 90

Poly(A)-containing RNA from Saccharomyces cerevisiae was translated in the wheat germ protein-synthesizing system and yielded as one of its products a polypeptide which was identified as invertase. This characterization was based on the presence of a protein band at 60,000 daltons following immunoprecipitation with a specific invertase antibody, and the formation from this protein of staphylococcal V8 protease and cyanogen bromide peptides, which were similar in size to those from carbohydrate-depleted invertase. The observed increase in invertase activity from the early to mid logarithmic stage of cell growth was synchronous with the appearance of translatable invertase mRN in these cells. No translatable invertase mRNA, however, was detected in late logarithmic cells, although a constant level of invertase activity was present in the culture medium.
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PMID:Growth phase dependence of invertase mRNA levels in yeast. 699 70

We have investigated the expression of protein kinase C (PKC) and protein kinase A (PKA) during the phases of growth and differentiation of the human colon carcinoma Caco-2 cells. We studied whether differentiation correlated with the responsiveness to cAMP and with an increased transport of the catalytic subunit of PKA into the nucleus. Also, we evaluated whether this phenomenon was affected by PKC activity. High levels of activated PKC were found in the plasma membranes of replicating cells. When the cells began to differentiate, plasma membrane-activated PKC decreased, while the cytosolic fraction increased. On the contrary, PKA holoenzyme increased during differentiation, along with the transport of its catalytic subunit into the nucleus. Both types I and II kinase A holoenzymes increased during differentiation, with maximal type II activity found when cells were fully differentiated. In replicating preconfluent cells, the inhibition of PKC by high dose phorbol 12-myristate 13-acetate or sphingosine increased the amount of both PKA catalytic subunit in the nucleus and sucrase activity. During differentiation, 8-Bromo-cAMP increased PKA catalytic subunit in the nucleus and apoliprotein A1 mRNA levels. These effects were inhibited by low-dose phorbol 12-myristate 13-acetate, which activates PKC in the plasma membranes. Our data suggest that PKC is activated in proliferating Caco-2 cells. The inhibition of PKC induces the transport of PKA catalytic subunit into the nucleus and the expression of the differentiation markers. Differentiated Caco-2 cells show a lower activation of PKC and an increased transport of the catalytic subunit of PKA into the nucleus.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The enterocyte-like differentiation of the Caco-2 tumor cell line strongly correlates with responsiveness to cAMP and activation of kinase A pathway. 781 34

The inhibitory effects of natural and synthetic inhibitors on the intestinal membrane-bound hydrolase, alpha-glucosidase (AGH), were evaluated by using an immobilized cyanogen bromide-activated Sepharose 4B support. Immobilized AGH (iAGH) inhibition study by synthetic inhibitors (acarbose and voglibose) revealed that the magnitude of inhibition differed from that in the free AGH (fAGH) study: IC50 value of acarbose in iAGH-maltase assay system, 340-430 nM; fAGH, 11 nM. iAGH-maltase inhibition by both inhibitors was influenced by blocking reagents with different functional groups (COOH, OH, CH3, and NH2 groups). On the other hand, significant iAGH-sucrase inhibitory activity was observed only when using the negatively charged support induced by 0.1 M beta-alanine. The Km values obtained in the iAGH assay system were similar to those from the fAGH method. With natural inhibitors, the iAGH-sucrase inhibitory activity of D-Xylose, with in vivo glucose suppression, increased twice compared to that in fAGH. Green tea extract gave almost the same inhibition for both AGH assay systems.
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PMID:Evaluation of alpha-glucosidase inhibition by using an immobilized assay system. 1099 9

Use of lectins as ligands for the immobilization and stabilization of glycoenzymes has immense application in enzyme research and industry. But their widespread use could be limited by the high cost of their production. In the present study preparation of a novel and inexpensive lectin support for use in the immobilization of glycoenzymes containing mannose or glucose residues in their carbohydrate moiety has been described. Cajanus cajan lectin (CCL) coupled covalently to cyanogen bromide activated Seralose 4B could readily bind enzymes such as invertase, glucoamylase and glucose oxidase. The immobilized and glutaraldehyde crosslinked preparations of invertase exhibited high resistance to inactivation upon exposure to enhanced temperature, pH, denaturants and proteolysis. Binding of invertase to CCL-Seralose was however found to be readily reversible in the presence of 1.0 M methyl alpha-D mannopyranoside. In a laboratory scale column reactor the CCL-Seralose bound invertase was stable for a month and retained more than 80% of its initial activity even after 60 days of storage at 4 degrees C. CCL-Seralose bound invertase exhibited marked stability towards temperature, pH changes and denaturants suggesting its potential to be used as an excellent support for the immobilization of other glycoenzymes as well.
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PMID:Immobilization and stabilization of invertase on Cajanus cajan lectin support. 1148 Sep 20

The biochemical reaction of a site-specific recombinase such as Hin invertase or gammadelta resolvase starts with binding of the recombinase to its recombination site and cleavage of the DNA in the center of the site. This is followed by strand exchange and finally ligation of the ends of the recombined strands. Previous biochemical studies have shown that Hin invertase and gammadelta resolvase cannot proceed beyond DNA cleavage in the absence of Mg++ ion, indicating that these recombinases require Mg++ ion in the strand exchange process. We have observed that the intercalating agent, ethidium bromide (2 microM), does not interfere with DNA cleavage, but slows strand exchange in a concentration-dependent manner. Levels of Mg++ ion below 5 mM also slow strand exchange substantially. We infer that random intercalation of ethidium bromide inhibits unwinding of the double helix at the recombination site in the negatively supercoiled DNA and propose that Mg+ may be required for Hin to deform the secondary structure of B-DNA prior to strand exchange.
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PMID:The effects of ethidium bromide and Mg++ ion on strand exchange in the Hin-mediated inversion reaction. 1474 29


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