Showing papers on "Enzyme assay published in 2003"
TL;DR: Experiments have indicated that [bmim]Cl, and several other ILs, as well as dimethylacetamide–LiCl (a well-known solvent system for cellulose), inactivate cellulase under these conditions.
380 citations
TL;DR: The enzyme activity was increased up to more than two-fold in presence of 2-mercaptoethanol, glutathione, and dithiothreitol, suggesting it to be a thiol-dependent serine protease.
352 citations
TL;DR: In this paper, a thermostable α-amylase producing Bacillus sp. ANT-6 was isolated from soil samples and the enzyme showed optimum activity at pH 10.5 and 80.5.
335 citations
TL;DR: Doses of dietary methylmercury in the range of 5 mg kg(-1) induces protective redox defences in the brain as seen from the induction of anti-oxidant enzyme SOD activity, however, above a threshold of 10 mg kg (-1) methylMERcury these defences are overcome and lipid peroxidative injury (TBARS) as well as severe pathological damage and adverse behaviour become apparent.
296 citations
TL;DR: The purpose of the research was to study the purification and partial characterization of thermostable serine alkaline protease from a newly isolated Bacillus subtilis PE-11, which was shown to have a relative low molecular weight and improve the cleansing power of various detergents.
Abstract: The purpose of the research was to study the purification and partial characterization of thermostable serine alkaline protease from a newly isolatedBacillus subtilis PE-11. The enzyme was purified in a 2-step procedure involving ammonium sulfate precipitation and Sephadex G-200 gel permeation chromatography. The enzyme was shown to have a relative low molecular weight of 15 kd by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and was purified 21-fold with a yield of 7.5%. It was most active at 60°C, pH 10, with casein as substrate. It was stable between pH 8 and 10. This enzyme was almost 100% stable at 60°C even after 350 minutes of incubation. It was strongly activated by metal ions such as Ca2+, Mg+2, and Mn+2. Enzyme activity was inhibited strongly by phenylmethyl sulphonyl fluoride (PMSF) and diisopropyl fluorophosphates (DFP) but was not inhibited by ethylene diamine tetra acetic acid (EDTA), while a slight inhibition was observed with iodoacetate,p-chloromercuric benzoate (pCMB), and β-mercaptoethanol (β-ME). The compatibility of the enzyme was studied with commercial and local detergents in the presence of 10mM CaCl2 and 1M glycine. The addition of 10mM CaCl2 and 1M glycine, individually and in combination, was found to be very effective in improving the enzyme stability where it retained 52% activity even after 3 hours. This enzyme improved the cleansing power of various detergents. It removed blood stains completely when used with detergents in the presence of 10mM CaCl2 and 1M glycine.
290 citations
TL;DR: A galactose derivative synthesized for chemical chaperone therapy of a human neurogenetic disease, β-galactosidosis, resulted in significant enhancement of the enzyme activity in the brain and other tissues and a marked decrease of intracellular substrate storage.
Abstract: We synthesized a galactose derivative, N-octyl-4-epi-β-valienamine (NOEV), for a molecular therapy (chemical chaperone therapy) of a human neurogenetic disease, β-galactosidosis (GM1-gangliosidosis and Morquio B disease). It is a potent inhibitor of lysosomal β-galactosidase in vitro. Addition of NOEV in the culture medium restored mutant enzyme activity in cultured human or murine fibroblasts at low intracellular concentrations, resulting in a marked decrease of intracellular substrate storage. Short-term oral administration of NOEV to a model mouse of juvenile GM1-gangliosidosis, expressing a mutant enzyme protein R201C, resulted in significant enhancement of the enzyme activity in the brain and other tissues. Immunohistochemical stain revealed a decrease in the amount of GM1 and GA1 in neuronal cells in the fronto-temporal cerebral cortex and brainstem. However, mass biochemical analysis did not show the substrate reduction observed histochemically in these limited areas in the brain probably because of the brief duration of this investigation. Chemical chaperone therapy may be useful for certain patients with β-galactosidosis and potentially other lysosomal storage diseases with central nervous system involvement.
253 citations
Journal Article•
TL;DR: Overexpression of MnSOD may be effective in growth suppression of pancreatic cancer and correlate enzyme activity with tumor growth, as well as determine whether tumor cell growth could be altered with antioxidant gene transfection.
Abstract: Chronic pancreatitis, K-ras oncogene mutations, and the subsequent generation of reactive oxygen species (ROS) appear to be linked to pancreatic cancer. ROS have also been suggested to be mitogenic and capable of stimulating cell proliferation. Cells contain antioxidant enzymes to regulate steady state levels of ROS produced by products of metabolism. The aims of our study were to determine antioxidant enzyme activity in pancreatic cancer cells and correlate enzyme activity with tumor growth, as well as determine whether tumor cell growth could be altered with antioxidant gene transfection. Western blots, enzyme activity, and enzyme activity gels were performed for manganese superoxide dismutase (MnSOD), copper/zinc, catalase, and glutathione peroxidase in normal human pancreas and in the human pancreatic cancer cell lines BxPC-3, Capan-1, MIA PaCa-2, and AsPC-1. Cell population doubling times were determined and correlated with antioxidant enzyme activity. MnSOD was overexpressed in MIA PaCa-2 using an adenoviral vector, and the effect on cell growth was determined. The cell pancreatic cancer lines BxPC-3, MIA PaCa-2, and AsPC-1 had decreased levels of MnSOD immunoreactive protein as well as activity and decreases in MnSOD levels correlated well with increased rates of tumor cell proliferation as determined by cell doubling time. No correlation could be found between cell growth and levels of copper/zinc superoxide dismutase, catalase, or glutathione peroxidase. Enforced expression of MnSOD by adenovirus transfection in the rapid growing cell line MIA PaCa-2 increased MnSOD immunoreactivity and MnSOD activity and decreased growth rate. Overexpression of MnSOD may be effective in growth suppression of pancreatic cancer.
216 citations
TL;DR: The data suggest that a cross-talk between Ca2+ and ROS originated from plasma membrane-bound NADPH oxidase is involved in the ABA signal transduction pathway leading to the induction of antioxidant enzyme activity, and Ca2- functions upstream as well as downstream of ROS production in the signalTransduction event in plants.
Abstract: The signal interactions between calcium (Ca2+) and reactive oxygen species (ROS) originated from plasma membrane NADPH oxidase in abscisic acid (ABA)-induced antioxidant defence were investigated in leaves of maize (Zea mays L.) seedlings. Treatment with ABA led to significant increases in the activity of plasma membrane NADPH oxidase, the production of leaf O2-, and the activities of several antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR). However, such increases were blocked by the pretreatment with Ca2+ chelator EGTA or Ca2+ channel blockers La3+ and verapamil, and NADPH oxidase inhibitors such as diphenylene iodonium (DPI), imidazole and pyridine. Treatment with Ca2+ also significantly induced the increases in NADPH oxidase activity, O2- production and the activities of antioxidant enzymes, and the increases were arrested by pretreatment with the NADPH oxidase inhibitors. Treatment with oxidative stress induced by paraquat, which generates O2-, led to the induction of antioxidant defence enzymes, and the up-regulation was suppressed by the pretreatment of Ca2+ chelator and Ca2+ channel blockers. Our data suggest that a cross-talk between Ca2+ and ROS originated from plasma membrane-bound NADPH oxidase is involved in the ABA signal transduction pathway leading to the induction of antioxidant enzyme activity, and Ca2+ functions upstream as well as downstream of ROS production in the signal transduction event in plants.
201 citations
TL;DR: Total Phenolic content of soybean leaves increased following chitosan and chitin oligomer treatments, showing a positive correlation between enzyme activity and total phenolic content.
201 citations
TL;DR: An organic solvent-tolerant bacterium producingorganic solvent-stable protease was isolated from fishing industry wastewater and identified as B. cereus, suggesting that the preparation contains metalloprotease(s).
197 citations
TL;DR: Regulation of the main metabolic pathways of Escherichia coli K12 was investigated based on 2-dimensional electrophoresis (2DE) and the measurement of enzyme activities, and protein abundance obtained by 2DE correlated well with enzyme activity, with a few exceptions.
Abstract: Regulation of the main metabolic pathways of Escherichia coli K12 was investigated based on 2-dimensional electrophoresis (2DE) and the measurement of enzyme activities. The cells were grown aerobically in different carbon sources, such as glucose, acetate, gluconate or glycerol. Microaerobic cultivation was also conducted with glucose as a carbon source. Fifty-two proteins could be identified based on 2DE, and 26 enzyme activities from the main metabolic pathways—including glycolysis, pentose phosphate pathway, TCA cycle, Entner-Doudoroff pathway and fermentative pathway—were assayed. These enzyme activities, together with global and quantitative protein expression, gave us a clear picture of metabolic regulation. The results show that, compared with the control experiment with glucose as a carbon source under aerobic conditions, glycolytic enzymes were slightly up-regulated ( 10-fold) under microaerobic conditions in glucose medium. When acetate was used as a carbon source, pfkA, pykF, ppc and zwf were down-regulated, while fbp, pckA, ppsA and mez were significantly up-regulated. Glyoxylate enzymes such as aceA and aceB were strongly up-regulated (>10-fold) and TCA-cycle-related enzymes were also up-regulated to some extent. With gluconate as a carbon source, edd, eda, fbp and TCA cycle enzymes were up-regulated. With glycerol as a carbon source, fbp and TCA cycle enzymes were up-regulated, while ackA was significantly down-regulated. Protein abundance obtained by 2DE correlated well with enzyme activity, with a few exceptions (e.g., isocitrate dehydrogenase), during aerobic growth on acetate.
TL;DR: Lipase from Aspergillus carneus was purified 24-fold with 38% yield using hydrophobic interaction chromatography and showed high levels of activity in the presence of many organic solvents and Mg ++ , Na + and NH 4 + ions.
TL;DR: The results suggest that theTransaminase from Vibrio fluvialis JS17 is a novel amine:pyruvate transaminase that has not been reported to date.
Abstract: A transaminase from Vibrio fluvialis JS17 showing activity toward chiral amines was purified to homogeneity and its enzymatic properties were characterized. The transaminase showed an apparent molecular mass of 100 kDa as determined by gel filtration chromatography and a subunit mass of 50 kDa by MALDI-TOF mass spectrometry, suggesting a dimeric structure. The enzyme had an isoelectric point of 5.4 and its absorption spectrum exhibited maxima at 320 and 405 nm. The optimal pH and temperature for enzyme activity were 9.2 and 37°C, respectively. Pyruvate and pyridoxal 5′-phosphate increased enzyme stability whereas (S)-α-methylbenzylamine reversibly inactivated the enzyme. The transaminase gene was cloned from a V. fluvialis JS17 genomic library. The deduced amino acid sequence (453 residues) showed significant homology with ω-amino acid:pyruvate transaminases (ω-APT) from various bacterial strains (80 identical residues with four ω-APTs). However, of 159 conserved residues in the four ω-APTs, 79 were not conserved in the transaminase from V. fluvialis JS17. Taken together with the sequence homology results, and the lack of activity toward β-alanine (a typical amino donor for the ω-APT), the results suggest that the transaminase is a novel amine:pyruvate transaminase that has not been reported to date.
TL;DR: Structural alterations and enzymatic activity modifications became significant within 24 h post-injection and recovery of hepatocytes on day 21 after microcystin-LR injection was evident, together with a decrease in the MC-LR equivalent content of the liver.
Abstract: After intraperitoneal injection of microcystin-LR (MC-LR) (125 μg kg−1 body wt.), the concentration of MC-LR in the liver of juvenile goldfish Carassius auratus (30 g body wt.) was assayed by a modified protein phosphatase inhibition method. A temporary accumulation occurred from 3 to 48 h post-injection, followed by a significant decrease between 48 and 96 h. Under our experimental conditions, contamination by MC-LR did not change ionic homeostasis, as attested by blood osmolality values and gill Na+/K+ ATPase activity. Light microscopy observations revealed lesions and cellular necrosis progression, which was concomitant with an increase in enzyme activity of plasma aspartate aminotransferase (AspAT), alanine aminotransferase (AlaAT) and l-lactate dehydrogenase (LDH) and with a decrease of hepatic glutathione-S-transferase (GST) activity. Structural alterations and enzymatic activity modifications became significant within 24 h post-injection. Recovery of hepatocytes on day 21 after MC-LR injection was evident, together with a decrease in the MC-LR equivalent content of the liver.
TL;DR: Northern blot analysis indicates that the mouse MGAT2 is most abundantly expressed in the small intestine, suggesting thatMGAT2 may play an important role in dietary fat absorption.
TL;DR: In this article, a wild strain of Penicillium sp in solid-state fermentation (SSF) was used as carbon and nitrogen source and solid matrix for synthesizing a serine protease.
TL;DR: It is demonstrated that the inhibition of enzyme activity at excess substrate concentration can be fully explained by transglycosylation of substrate molecules and the novel convenient chitotriosidase enzyme assay should facilitate the accurate monitoring of Gaucher disease patients receiving costly enzyme replacement therapy.
TL;DR: It is confirmed that MHBD deficiency is caused by mutations in the HADH2 gene, a short-chain 3-hydroxyacyl-CoA dehydrogenase also known as the "endoplasmic reticulum-associated amyloid-beta binding protein" (ERAB).
Abstract: 2-methyl-3-hydroxybutyryl-CoA dehydrogenase (MHBD) deficiency is a novel inborn error of isoleucine degradation. In this article, we report the elucidation of the molecular basis of MHBD deficiency. To this end, we purified the enzyme from bovine liver. MALDI-TOF mass spectrometry analysis revealed that the purified protein was identical to bovine 3-hydroxyacyl-CoA dehydrogenase type II. The human homolog of this bovine enzyme is a short-chain 3-hydroxyacyl-CoA dehydrogenase, also known as the “endoplasmic reticulum–associated amyloid-β binding protein” (ERAB). This led to the identification of the X-chromosomal gene involved, which previously had been denoted “HADH2.” Sequence analysis of the HADH2 gene from patients with MHBD deficiency revealed the presence of two missense mutations (R130C and L122V). Heterologous expression of the mutant cDNAs in Escherichia coli showed that both mutations almost completely abolish enzyme activity. This confirms that MHBD deficiency is caused by mutations in the HADH2 gene.
TL;DR: A laccase isolated from the fully browned gills of Lentinula edodes fruit bodies was able to oxidize phenolic compounds extracted from fresh gills to brown-coloured products, suggesting a role for lacc enzyme in melanin synthesis in this strain.
Abstract: A laccase (EC 1.10.3.2) was isolated from the fully browned gills of Lentinula edodes fruit bodies. The enzyme was purified to a homogeneous preparation using hydrophobic, cation-exchange and size-exclusion chromatography. SDS-PAGE analysis showed the purified laccase, Lcc 2, to be a monomeric protein of 58·0 kDa. The enzyme had an isoelectric point of around pH 6·9. The optimum pH for enzyme activity was around 3·0 against 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS), and it was most active at 40 °C and stable up to 50 °C. The enzyme contained 8·6 % carbohydrate and some copper atoms. The enzyme oxidized ABTS, p-phenylenediamine, pyrogallol, guaiacol, 2,6-dimethoxyphenol, catechol and ferulic acid, but not veratryl alcohol and tyrosine. β-(3,4-Dihydroxyphenyl)alanine (l-DOPA), which was not oxidized by a laccase previously reported from the culture filtrate of L. edodes, was also oxidized by Lcc 2, and the oxidative product of l-dopa was identified as l-DOPA quinone by HPLC analysis. Lcc 2 was able to oxidize phenolic compounds extracted from fresh gills to brown-coloured products, suggesting a role for laccase in melanin synthesis in this strain.
TL;DR: This article showed that methyl jasmonate (MeJA) stimulated soyasaponin biosynthesis in cultured cells of Glycyrrhiza glabra (common licorice).
Abstract: Exogenously applied methyl jasmonate (MeJA) stimulated soyasaponin biosynthesis in cultured cells of Glycyrrhiza glabra (common licorice). mRNA level and enzyme activity of beta-amyrin synthase (bAS), an oxidosqualene cyclase (OSC) situated at the branching point for oleanane-type triterpene saponin biosynthesis, were up-regulated by MeJA, whereas those of cycloartenol synthase, an OSC involved in sterol biosynthesis, were relatively constant. Two mRNAs of squalene synthase (SQS), an enzyme common to both triterpene and sterol biosyntheses, were also up-regulated by MeJA. In addition, enzyme activity of UDP-glucuronic acid: soyasapogenol B glucuronosyltransferase, an enzyme situated at a later step of soyasaponin biosynthesis, was also up-regulated by MeJA. Accumulations of bAS and two SQS mRNAs were not transient but lasted for 7 d after exposure to MeJA, resulting in the high-level accumulation (more than 2% of dry weight cells) of soyasaponins in cultured licorice cells. In contrast, bAS and SQS mRNAs were coordinately down-regulated by yeast extract, and mRNA accumulation of polyketide reductase, an enzyme involved in 5-deoxyflavonoid biosynthesis in cultured licorice cells, was induced transiently by yeast extract and MeJA, respectively.
TL;DR: A broad screening of 58 fungi including 46 white rot strains on solid media resulted in the selection of 13 white rot fungi, which were active in decolourising the poly R-478 lignin model and were capable of growing on crude olive oil mill wastewaters (OOMW) with a COD of 100 ǫl −1.
TL;DR: An assay strategy for determining the substrate for denitrase was developed combining 2D-gel electrophoresis and an on-blot enzyme assay and the resulting substrate was Histone H1.2, an isoform protein of linker histone, which has only one tyrosine residue in the entire molecule.
Abstract: Several reports have described an activity that modifies nitrotyrosine-containing proteins and their immunoreactivity to nitrotyrosine Abs. Without knowing the product of the reaction, this new activity has been called a “denitrase.” In those studies, some nonspecific proteins, which have multiple tyrosine residues, e.g., albumin, were used as a substrate. Therefore, the studies were based on an unknown mechanism of reaction and potentially a high background. To solve these problems, one of the most important things is to find a more suitable substrate for assay of the enzyme. We developed an assay strategy for determining the substrate for denitrase combining 2D-gel electrophoresis and an on-blot enzyme assay. The resulting substrate from RAW 264.7 cells was Histone H1.2, an isoform protein of linker histone. Histone H1.2 has only one tyrosine residue in the entire molecule, which ensures the exact position of the substrate to be involved. It has been reported that Histones are the most prominent nitrated proteins in cancer tissues. It was also demonstrated that tyrosine nitration of Histone H1 occurs in vivo. These findings lead us to the idea that Histone H1.2 might be an intrinsic substrate for denitrase. We nitrated recombinant and purified Histone H1.2 chemically and subjected it to an on-blot enzyme assay to characterize the activity. Denitrase activity behaved as an enzymatic activity because the reaction was time dependent and was destroyed by heat or trypsin treatment. The activity was shown to be specific for Histone H1.2, to differ from proteasome activity, and to require no additional cofactors.
TL;DR: Results indicate that S-nitrosylation of cysteine residues on ICDH is a mechanism involving the inactivation of I CDH by peroxynitrite, which may result in the perturbation of the cellular antioxidant defense mechanisms and subsequently lead to a pro-oxidant condition.
TL;DR: The early and noticeable development of digestive enzyme activities was linked to a high survival after weaning, and variations observed in the activity profiles of the digestive enzymes were correlated either to developmental events or to changes in the nature of the diet.
Abstract: Activity of some of the main enzymes involved in protein digestion and absorption (acid and alkaline professes, leucine-aminopeptidase, acid and alkaline phosphatases) as well as those of amylase and lipase, was assessed during larval development of while sea bream Diplodus sargus. All enzyme activity was detected at the moment of mouth opening. The variations observed in the activity profiles of the digestive enzymes were correlated either to developmental events. such as the functional start of the stomach (22 days after hatching), or to changes in the nature of the diet. The early and noticeable development of digestive enzyme activities was linked to a high survival after weaning.
TL;DR: An insect cell expression system used for the generation of large amounts of recombinant protein of high specific activity is presented here for the first time and it is confirmed that the 8 kDa subunit is essential for enzyme activity.
Abstract: The mammalian endoglycosidase heparanase (Hpa1) is primarily responsible for cleaving heparan sulphate proteoglycans (HSPGs) present on the basement membrane of cells and its potential for remodelling the extracellular matrix (ECM) could be important in embryonic development and tumour metastasis. Elevated expression of this enzyme has been implicated in various pathological processes including tumour cell proliferation, metastasis, inflammation and angiogenesis. The enzyme therefore represents a potential therapeutic target. Hpa1 protein is initially synthesized as an inactive 65 kDa proenzyme that is then believed to be subsequently activated by proteolytic cleavage to generate an active heterodimer of 8 and 50 kDa polypeptides. By analysis of a series of Hpa1 deletion proteins we confirm that the 8 kDa subunit is essential for enzyme activity. We present here for the first time an insect cell expression system used for the generation of large amounts of recombinant protein of high specific activity. Individual subunits were cloned into baculoviral secretory vectors and co-expressed in insect cells. Active secreted heterodimer protein was recovered from the medium and isolated by a one-step heparin-Sepharose chromatography procedure to give protein of >90% purity. The recombinant enzyme behaved similarly to the native protein with respect to the size of HS fragments liberated on digestion, substrate cleavage specificity and its preference for acidic pH. A significant amount of activity, however, was also detectable at physiological pH values, as measured both by an in vitro assay and by in vivo degradation of cell-bound heparan sulphate.
TL;DR: Results suggest that cytosolic G6PDH activity is regulated by sugar availability at the transcriptional level, and in extended dark periods, G6 PDH activity in the stroma is restricted but can be stimulated in response to high demands for NADPH.
Abstract: In plants, Glc-6-phosphate dehydrogenase (G6PDH) isoenzymes are present in the cytosol and in plastids. The plastidic enzymes (P1 and P2) are subject to redox regulation, but mechanisms that adjust cytosolic G6PDH activity are largely unknown. We adopted a leaf disc system for monitoring the effects of various conditions on G6PD isoform expression and enzyme activities in potato (Solanum tuberosum). Cytosolic G6PDH activity remained constant during water incubation in the dark. In continuous light or in the presence of metabolizable sugars in the dark, cytosolic G6PDH activity increased 6-fold within 24 h. Cycloheximide incubation demonstrated that enhanced cytosolic G6PDH activity depends on de novo protein synthesis. Osmotic change, phosphate sequestration, or oxidative stress did not affect cytosolic G6PDH activity. Furthermore, enzyme activity and protein contents closely followed the corresponding mRNA levels. Together with the fact that multiple SURE elements are present in the promoter region of the gene, these results suggest that cytosolic G6PDH activity is regulated by sugar availability at the transcriptional level. Plastidic G6PDH activity stayed constant during water incubation in the light and dropped to minimal levels within 6 h in the dark. Conversely, plastidic G6PDH activity of leaf discs incubated on Paraquat rose to 10-fold higher levels, which was not prevented by cycloheximide. Similar increases were found with nitrite, nitrate, or sulfate. No major changes in protein or mRNA contents of the plastidic P1 and P2 isoforms were registered. K(m) (Glc-6-phosphate) values of plastidic G6PDH activity differed between samples incubated on water or Paraquat, suggesting posttranslational modification of the plastidic enzyme(s). Immunoprecipitation of (32)P-labeled samples with P1 isoform-specific antibodies showed that the chloroplast enzyme is subject to protein phosphorylation. Obviously, in extended dark periods, G6PDH activity in the stroma is restricted but can be stimulated in response to high demands for NADPH.
TL;DR: The enzyme was able to hydrolyze both soluble and insoluble emulsified substrates and was classified as a lipase, expressing some esterase activity as well, and the most advantageous method for immobilization was found to be ionic binding to DEAE Cellulose.
Abstract: Extracellular thermostable lipase produced by the thermophilic Bacillus stearothermophilus MC 7 was purified to 19.25-fold with 10.2% recovery. The molecular weight of the purified enzyme determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was shown to be 62 500 Da. The purified enzyme expressed maximum activity at 75-80 OC and its half life was 30min at 70 OC. The K,,, and V,,,,, were calculated to be, respectively, 0.33 mM and 188 pMmin-' mg-' withp-nitrophenyl palmitate @NPP) as a substrate. Enzyme activity was inhibited by divalent ions of heavy metals, thiol and serine inhibitors, whereas calcium ion stimulated its activity. The most advantageous method for immobilization was found to be ionic binding to DEAE Cellulose. The enzyme was able to hydrolyze both soluble and insoluble emulsified substrates and was classified as a lipase, expressing some esterase activity as well. 0 2003 Elsevier Science B.V. All rights reserved.
TL;DR: The changes in the levels of lipid peroxidation and antioxidant enzyme activities which were determined in different tissues of hypothyroid rats indicate a cause for functional disorder of these tissues.
Abstract: Free radicals are now well known to damage cellular components. To investigate whether age and thyroid level affect peroxidation speed, we examined the levels of malondialdehyde and antioxidant enzyme activities in different age groups of hypothyroid rats. Hypothyroidism was induced in 30- and 60-day-old Wistar Albino rats by the i.p. administration of propylthiouracil (10 mg kg−1 body weight) for 15 days. While malondialdehyde levels of 30- or 60-day-old hypothyroid rats were increased in liver, they were decreased in the tissues of the heart and thyroid. While glucose-6-phosphate dehydrogenase activity levels did not change in heart, brain and liver tissues of 30-day-old rats, they increased in brain and heart tissues of 60-day-old experimental groups, but decreased in the liver. Catalase activities decreased in the liver and heart of rats with hypothyroidism, but increased in erythrocytes. In control groups while malondialdehyde levels increased in brain, heart and thymus with regard to age, they decreased in plasma. Glucose-6-phosphate dehydrogenase and catalase activities were not affected by age in tissues of the thymus, thyroid and brain, but they were decreased in the heart tissue. The changes in the levels of lipid peroxidation and antioxidant enzyme activities which were determined in different tissues of hypothyroid rats indicate a cause for functional disorder of these tissues. Moreover, there may be changes depending on age at lipid peroxidation and antioxidant enzyme activity levels. Copyright © 2003 John Wiley & Sons, Ltd.
TL;DR: The fenofibrate-induced elevation of HDL-associated PAF-AH activity in dyslipidemic patients of Type IIB and Type IV, as well as the reduction in enzyme activity associated with atherogenic apoB-containing lipoproteins in all patient groups, may represent a new and important antiatherogenic effect of this potent lipid-modulating agent.
TL;DR: The results indicate the complex interactive effects adsorption of enzymes to clay particles can have on the availability and capability of hydrolysis, reduction of enzyme reactivity, storage attached to clay particle with changes in transport and distribution, and protection from photodegradation.
Abstract: Enzymes released extracellularly by micro-organisms have major functions in nutrient acquisition and organic matter degradation. Clay particles, common in many surface waters, can modify enzyme activity. Clay minerals are known to form aggregates with organic molecules, and the formation of enzyme-clay complexes could alter the level of activity. Montmorillonite clay and clay extracted from Elledge Lake (Tuscaloosa, Alabama) basin soil were combined with alkaline phosphatase, glucosidase, protease, and xylosidase solutions to assess adsorption and the effect of this adsorption on enzyme activity. Adsorption to Elledge Lake basin clay decreased alkaline phosphatase activity, and adsorption to montmorillonite was observed for all four enzymes with reductions in enzyme activities. Adsorption of substrate onto clay surfaces resulted in a concentration effect and increased enzyme activity associated with the particles. When enzyme-clay complexes were exposed to natural sunlight there was a decrease in enzyme activity, but this decrease was usually not significantly different from the adsorption only treatment. The formation of enzyme-clay complexes may serve to protect the enzymes from natural in situ photodegradation. The results indicate the complex interactive effects adsorption of enzymes to clay particles can have on the availability and capability of hydrolysis – reduction of enzyme reactivity, storage attached to clay particles with changes in transport and distribution, and protection from photodegradation.