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1دورية أكاديمية
المصدر: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
مصطلحات موضوعية: Dehydration, Lactate dehydrogenase, Urea, Xenopus laevis
الوصف: The African clawed frog, Xenopus laevis endures whole body dehydration which can increase its reliance on anaerobic glycolysis for energy production. This makes the regulation of the terminal enzyme of glycolysis, lactate dehydrogenase (LDH), crucial to stress survival. We investigated the enzymatic properties and posttranslational modification state of purified LDH from the skeletal muscle of control and dehydrated (30% total body water loss) X. laevis. LDH from the muscle of dehydrated frogs showed a 93% reduction in phosphorylation on threonine residues and an 80% reduction of protein nitrosylation. LDH from dehydrated muscle also showed a 74% lower Vmax in the pyruvate oxidizing direction and a 78% decrease in Vmax in the lactate reducing direction along with a 33% lower Km for pyruvate and a 40% higher Km for lactate. In the presence of higher levels of urea and molecular crowding by polyethylene glycol, used to mimic conditions in the cells of dehydrated animals, the Km values of control and dehydrated LDH demonstrated opposite responses. In the pyruvate oxidizing direction, control muscle LDH was unaffected by these additives, whereas the affinity for pyruvate dropped further for LDH from dehydrated muscle. The opposite effect was more pronounced in the lactate reducing direction as control LDH showed an increased affinity for lactate, whereas LDH from dehydrated animals showed a further reduction in affinity. The physiological consequences of dehydration-induced LDH regulation appear to poise the enzyme towards lactate production when urea levels are high and lactate catabolism when urea levels are low, perhaps helping to maintain glycolysis under dehydrating conditions whilst providing for the ability to recycle lactate upon rehydration.
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2دورية أكاديمية
المؤلفون: Mosiichuk, N.M. (Nadia M.), Maksymiv, I.V. (Ivan V.), Husak, V.V. (Viktor V.), Storey, J. (Janet M.), Storey, K. (Kenneth B.), Lushchak, V.I. (Volodymyr I.)
المصدر: Turkish Journal of Fisheries and Aquatic Sciences vol. 18 no. 10, pp. 1177-1185
مصطلحات موضوعية: Blood parameters, Glycogen, Lactate dehydrogenase, Transaminases, Triacylglycerol
الوصف: The impact of goldfish exposure for 96 h to herbicide Gesagard 500 FW at concentrations 0.2, 1, or 5 mg L−1 (corresponding to 0.1, 0.5 or 2.5 mg L-1 of effective compound prometryn) on the hematological profile of blood and biochemical parameters of plasma and liver was studied. Fish exposure to low concentration of the herbicide (0.2 mg L-1) slightly decreased liver glycogen and plasma lactate levels. Plasma glucose levels rose by 27% in goldfish exposed to 1 mg L-1 Gesagard. The activity of lactate dehydrogenase decreased by 63% and 36% in plasma of fish exposed to herbicide at concentrations 1 and 5 mg L-1, respectively, but was not affected in liver. Goldfish exposure to the highest concentration of Gesagard (5 mg L-1) decreased hematocrit by 23% and increased monocyte count by 57%, and elevated triacylglycerol level by 91% in plasma. Overall, the results indicate that acute exposure to Gesagard induced minor changes in the hematological and biochemical parameters of goldfish, suggesting that disruptions of these parameters may provide early warning signs that could be useful for assessing acute or sublethal toxic effects of pesticides on aquatic species.
الإتاحة: https://doi.org/10.4194/1303-2712-v18_10_04Test
https://ir.library.carleton.ca/pub/18305Test -
3دورية أكاديمية
المؤلفون: Storey, K. (Kenneth B.)
المصدر: Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology vol. 199, pp. 13-20
مصطلحات موضوعية: Enzyme adaptation, Hypometabolism, Lactate dehydrogenase, Metabolic regulation, Posttranslational modification, Protein acetylation, Reversible protein phosphorylation
الوصف: Comparative enzymology explores the molecular mechanisms that alter the properties of enzymes to best fit and adapt them to the biotic demands and abiotic stresses that affect the cellular environment in which these protein catalysts function. For many years, comparative enzymology was primarily concerned with analyzing enzyme functional properties (e.g. substrate affinities, allosteric effectors, responses to temperature or pH, stabilizers, denaturants, etc.) in order to determine how enzyme properties were optimized to function under changing conditions. More recently it became apparent that posttranslational modifications of enzymes play a huge role in metabolic regulation. At first, such modifications appeared to target just crucial regulatory enzymes but recent work is showing that many dehydrogenases are also targets of posttranslational modification leading to substantial changes in enzyme properties. The present article focuses in particular on lactate dehydrogenase (LDH) showing that stress-induced changes in enzyme properties can be linked with reversible posttranslational modifications; e.g. changes in the phosphorylation state of LDH occur in response to dehydration stress in frogs and anoxia exposure of turtles and snails. Furthermore, these studies show that LDH is also a target of other posttranslational modifications including acetylation, methylation and ubiquitination that change in response to anoxia or dehydration stress. Selected new methods for exploring posttranslational modifications of dehydrogenases are discussed and new challenges for the future of comparative enzymology are presented that will help to achieve a deeper understanding of biochemical adaptation through enzyme regulation.
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4دورية أكاديمية
المؤلفون: Childers, C.L. (Christine L.), Green, S.R. (Stuart R.), Dawson, N.J. (Neal J.), Storey, K. (Kenneth B.)
المصدر: Analytical Biochemistry vol. 508, pp. 144-117
مصطلحات موضوعية: Differential scanning fluorimetry, Enzyme kinetics, Enzyme stability, Lactate dehydrogenase, Native denaturation, Urea
الوصف: The effect of protein stability on kinetic function is monitored with many techniques that often require large amounts of expensive substrates and specialized equipment not universally available. We present differential scanning fluorimetry (DSF), a simple high-throughput assay performed in real-time thermocyclers, as a technique for analysis of protein unfolding. Furthermore, we demonstrate a correlation between the half-maximal rate of protein unfolding (Knd), and protein unfolding by urea (I50). This demonstrates that DSF methods can determine the structural stability of an enzyme's active site and can compare the relative structural stability of homologous enzymes with a high degree of sequence similarity.
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5دورية أكاديميةCatalase activity as a potential vital biomarker of fish intoxication by the herbicide aminotriazole
المؤلفون: Vasylkiv, O.Y. (Olena Yu.), Kubrak, O.I. (Olga I.), Storey, K. (Kenneth B.), Lushchak, V.I. (Volodymyr I.)
المصدر: Pesticide Biochemistry and Physiology vol. 101 no. 1, pp. 1-5
مصطلحات موضوعية: 3-Amino-1,2,4-triazole, Carassius auratus, Catalase, Erythrocytes, Hemoglobin, Lactate dehydrogenase, Plasma
الوصف: The objective of this study was to investigate the effects of the herbicide 3-amino-1,2,4-triazole (AMT) on the activities of catalase and lactate dehydrogenase (LDH) in blood (plasma and erythrocytes) and eight solid tissues of goldfish, Carassius auratus. Injection of goldfish with AMT (0.5. mg/gww AMT in 0.9% NaCl) resulted in a significant decrease in catalase activity 24. h post-injection in most tissues investigated. In white and red muscle, kidney, heart, liver, brain and erythrocytes the activity of catalase decreased by 61%, 69%, 64%, 48%, 40
الإتاحة: https://doi.org/10.1016/j.pestbp.2011.05.005Test
https://ir.library.carleton.ca/pub/5701Test -
6دورية أكاديمية
المؤلفون: Vasylkiv, O.Y. (Olena Yu.), Kubrak, O.I. (Olha I.), Storey, K. (Kenneth B.), Lushchak, V.I. (Volodymyr I.)
المصدر: Chemosphere vol. 80 no. 9, pp. 1044-1049
مصطلحات موضوعية: Carassius auratus, Catalase, Erythrocytes, Hemoglobin, Lactate dehydrogenase, Plasma
الوصف: Chromium ions are frequently found in aquatic ecosystems and are known to be inducers of oxidative stress in fish solid tissues. The present study was designed to determine whether fish blood samples can be used to allow nonlethal diagnostic testing for chromium intoxication. First, we confirmed that 96h exposures to water containing 10.0mgL -1 chromium ions, either Cr 3+ or Cr 6+, induced oxidative stress in brain of goldfish (Carassius auratus). Multiple blood parameters were then evaluated. Cr 6+ exposure triggered a 579% increase in the number of erythrocytes containing micronuclei, a frequently used ma
الإتاحة: https://doi.org/10.1016/j.chemosphere.2010.05.023Test
https://ir.library.carleton.ca/pub/5043Test -
7دورية أكاديمية
المؤلفون: Lushchak, V.I. (Volodymyr I.), Lushchak, L.P. (Ljudmyla P.), Bahnjukova, T.V. (Tetjana V.), Spichenkov, A.V. (Alexei V.), Storey, K. (Kenneth B.)
المصدر: Biochemistry and Cell Biology vol. 76 no. 4, pp. 609-614
مصطلحات موضوعية: Enzyme binding, Hexokinase, Lactate dehydrogenase, Pyruvate kinase, Scorpaena porcus
الوصف: Free and bound forms of hexokinase, pyruvate kinase, and lactate dehydrogenase were prepared from the brain of the sea scorpion (Scorpaena porcus) in a low ionic strength medium. Properties of the free and bound forms were compared to determine whether binding to particulate matter could influence enzyme function or stability in vivo. Changes in pH differently affected the activity of the free and bound forms of all three enzymes. Furtherm
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8دورية أكاديمية
المصدر: Biochemistry and Molecular Biology International vol. 43 no. 3, pp. 685-694
مصطلحات موضوعية: AMP-deaminase, Corb, Enzyme binding, Lactate dehydrogenase, Pyruvate kinase, Sciena umbra, Scorpaena porcus, Sea scorpion, Solubilization
الوصف: A previous study described an unusual influence of neutral salts on the behavior of trout muscle AMP-deaminase (AMPD) in its interactions with subcellular particulate matter. The present study shows that this behavior is also shared by the muscle enzyme of two other fish species, sea scorpion (Scorpaena porcus) and corb (Sciena umbra), indicating that this describes a principle for AMPD interaction with cellular particulate material. AMPD binding to particulate matter increased with increasing KCl concentration through the physiological range (100-200 mM), but at higher salt concentrations the amount of bound enzyme was reduced. The pattern of binding was not influenced by hydrophobic interactions since addition of the nonionic detergents, Triton X-100 or Tween-80, did not alter the distribution of bound versus free enzyme although both detergents, at low concentrations, enhanced enzyme maximal activity. AMPD binding to particulate matter was also influenced by pH, the amount of free enzyme rising by nearly 3-fold as pH fell within the physiological range from 7.5 to 6.5. It is concluded that neither electrostatic nor hydrophobic forces alone can account for the unusual solubilization of AMPD from fish muscle and it is possible that the effect is also related to ion-induced conformational changes in the structure of AMPD and/or of the myosin to which the enzyme binds.
