Enzymatic activity

A pot culture experiment was conducted to study the effect of humic acid on soil microbial population and enzymatic activity in groundnut in an Alfisol at Main Agricultural Research Station, Dharwad.

5p gaocaolon5 14-06-2020 6 1   Download

With the aim to distinguish between local and global conformational changes induced by trifluoroethanol in RNase A, spectroscopic and activity measurements in combination with proteolysis by unspecific proteases have been exploited for probing structural transitions of RNase A as a function of trifluoroethanol concentration. At 30% (v/v) trifluoroethanol (pH 8.0; 25 °C), circular dichroism and fluorescence spectroscopy indicate a cooperative collapse of the tertiary structure of RNase A coinciding with the loss of its enzymatic activity....

7p system191 01-06-2013 49 3   Download

An exo-1,3-b-glucanase has been isolated from cultural filtrate of Trichoderma viride AZ36. The N-terminal sequence of the purified enzyme (m ¼ 61 ^ 1 kDa) showed no significant homology to other known glucanases. The 1,3-b-glucanase displayed high activity against laminarins, curdlan, and 1,3-b-oligoglucosides, but acted slowly on 1,3-1,4-b-oligoglucosides. No significant activity was detected against high molecular mass 1,3-1,4-bglucans. The enzyme carried out hydrolysis with inversion of the anomeric configuration.

9p system191 01-06-2013 47 6   Download

This study investigated the enzymatic function of two putative plant GPXs, GPXle1 from Lycopersicon esculentum and GPXha2 from Helianthus annuus, which show sequence identities with the mammalian phospholipid hydroperoxide glutathione peroxidase (PHGPX). Both purified recombinant proteins expressed in Escherichia coli show PHGPX activity by reducing alkyl, fatty acid and phospholipid hydroperoxides but not hydrogen peroxide in the presence of glutathione.

7p research12 01-06-2013 37 4   Download

Nuclear receptors (NRs) are ligand-regulated, DNA-binding transcription factors that function in the chromatin environment of the nucleus to alter the expression of subsets of hormone-responsive genes. It is clear that chromatin, rather than being a passive player, has a profound effect on both transcriptional repression and activation mediated by NRs.

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By replacing specific amino acids at positions 112, 147 and 152 of the human aldosterone synthase (CYP11B2) with the corresponding residues from human, mouse or rat 11b-hydroxylase (CYP11B1), we have been able to investigate whether these residues belong to structural determinants of individual enzymatic activities. When incubated with 11-deoxycorticosterone (DOC), the 11b-hydroxylation activity of the mutants was most effectively increased by combining D147E and I112P (sixfold increase).

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We have recently expressed in bacteria the enzymatically active reverse transcriptase (RT) of bovine leukemia virus (BLV) [Perach, M. & Hizi, A. (1999) Virology 259, 176–189]. In the present study, we have studied in vitro two features of the DNA polymerase activity of BLV RT, the processivity of DNA synthesis and the fidelity of DNA synthesis. These properties were compared with those of the well-studied RTs of human immunodeficiency virus type 1 (HIV-1) and murine leukaemia virus (MLV).

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The thermal stabilityofperoxidase fromleavesof theAfrican oil palm treeElaeis guineensis(AOPTP) at pH 3.0 was studied by differential scanning calorimetry (DSC), intrinsic fluorescence, CD and enzymatic assays.The spectral parameters asmonitoredby ellipticity changes in the far-UV CD spectrum of the enzyme as well as the increase in tryp-tophan intensity emission upon heating, together with changes in enzymatic activity with temperature were seen to be good complements to the highly sensitive but integral methodofDSC....

7p research12 29-04-2013 46 3   Download

Glutathione reductase (GR) recycles oxidized glutathione (GSSG) by converting it to the reduced form (GSH) using an NADPH as the electron source. The function of GR in the male genital tract of the rat was examined by meas-uring its enzymatic activity and examining the gene expression and localization of the protein.

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Theb1,3-glycosyltransferase enzymes identi®ed to date share several conserved regions and conserved cysteine res-idues, all being located in the putative catalytic domain. To investigate the importance of these motifs and cysteines for the enzymatic activity, 14 mutants of the murine b1,3-galactosyltransferase-I gene were constructed and expressed in Sf9 insect cells. Seven mutations abolished the galacto-syltransferase activity.

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It is scientifically and industrially important 1 to clarify the stabilizing mechanism of proteases in extraordinary envi-ronments. We used subtilisins ALPI and Sendai as models to study the mechanism. Subtilisin ALPI is extremely sensitive to highly alkaline conditions, even though the enzyme is produced by alkalophilicBacillus, whereas sub-tilisin Sendai from alkalophilic Bacillusis stable under conditions of high alkalinity.

9p research12 23-04-2013 48 2   Download

Reactionof certainpeptides andproteinswithsingletoxygen (generated by visible light in the presence of rose bengal dye) yields long-lived peptide and protein peroxides. Incubation of these peroxides with glyceraldehyde-3-phosphate dehy-drogenase, in the absence of addedmetal ions, results in loss of enzymatic activity. Comparative studies with a range of peroxides have shown that this inhibition is concentration, peroxide, and time dependent, with H2O2less ecient than some peptide peroxides.

10p research12 23-04-2013 39 4   Download

The mature cysteine protease from Dermatophgoides pteronyssinus, Der p 1, is a major house dust mite allergen. Its enzymatic activity has been shown to have pro-in¯am-matory e€ects that could alsonegatively in¯uence ecacy of allergen-speci®c immunotherapy. The aimof this study was to express recombinant pro-Der p 1 (rpro-Der p 1) in the yeastPichia pastorisand to study itsmaturation.

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A novel nucleosidase enzymatic activity was discovered in the marine spongeAxinella polypoides. This enzyme, desig-nated as ATP N-glycosidase, converts adenosine-5¢-tri-phosphate into adenine and ribose-5-triphosphate. The crude extract ofA.polypoideswas capable of hydrolysing 25lmol ATPÆmin )1 per g wet weight of sponge. The cata-lytic activity of a sponge crude extract permg total protein is comparable with specific activities of purified plant adeno-sine and bacterial AMP nucleosidases.

11p tumor12 20-04-2013 56 3   Download

Earlier we presented several lines of evidence that a 67-kDa laminin binding protein (LBP) inLeishmania donovani,that is different from the putative mammalian 67-kDa laminin receptor, may play an important role in the onset of leish-maniasis, as these parasites invade macrophages in various organs after migrating through the extracellular matrix. Here we describe the membrane orientation of thisLeish-manialaminin receptor.

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Novel chromogenic substrates for endo-b-galactosidase were designed on the basis of the structural features of keratan sulfate. Galb1-4GlcNAcb1-3Galb1-4GlcNAcb-pNP (2),which consists of two repeating units ofN-acetyl-lactosamine,was synthesized enzymatically by consecutive additions of GlcNAc and Gal residues top-nitrophenyl b-N-acetyllactosaminide. In a similar manner,Glc-NAcb1-3Galb1-4GlcNAcb-pNP (1),GlcNAcb1-3Galb1-4Glcb-pNP (3),Galb1-4GlcNAcb1-3Galb1-4Glcb-pNP (4), Galb1-3GlcNAcb1-3Galb1-4Glcb-pNP (5),and Galb1-6GlcNAcb1-3Galb1-4Glcb-pNP (6) were synthesized as analogues of2.

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A100-kDa proteinwith endoglucanase activitywas purified from Triton X-100 extract of cells of the thermoacidophilic Gram-positive bacterium Alicyclobacillus acidocaldarius. The enzyme exhibited activity towards carboxy methyl cel-lulose and oat spelt xylan with pH and temperature optima of 4 and 80
C, respectively. Cloning and nucleotide sequence analysis of the corresponding gene (celB) revealed an ORF encoding a preprotein of 959 amino acids which is consistent with an extracellular localization.

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We showed expression of the tryptophan hydroxylase gene and of tryptophan hydroxylase protein immunoreactivity in mouse skin and skin cells. Extracts from skin and melano-cyte samples acetylated serotonin toN-acetylserotonin and tryptamine toN-acetyltryptamine. A different enzyme from arylalkylamineN-acetyltransferase mediated this reaction, as this gene was defective in the C57BL6 mouse, coding predominantly for a protein without enzymatic activity. Serotonin (but not tryptamine) acetylation varied according to hair cycle phase and anatomic location....

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The major cellulase secreted by the filamentous fungus Trichoderma reeseiis cellobiohydrolase Cel7A. Its three-dimensional structure has been solved and various mutant enzymes produced. In order to study the potential use of T. reeseiCel7A in the alkaline pHrange, the thermal sta-bilityofCel7Awas studiedas a functionof pHwith thewild-type and two mutant enzymes using different spectroscopic methods. Tryptophan fluorescence and CD measurements of the wild-type enzyme show an optimal thermostability between pH3.5–5.

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ADH1 and ADH4 are the major alcohol dehydrogenases (ADH) in ethanol and retinol oxidation. ADH activity and protein expression were investigated in rat gastrointestinal tissuehomogenates by enzymatic andWesternblot analyses. In addition, sections of adult rat gastrointestinal tract were examined byin situ hybridization and immunohistochem-istry.ADH1andADH4weredetectedalong thewhole tract, changing their localization and relative content as a function of the area studied.

11p fptmusic 16-04-2013 36 2   Download