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1
المؤلفون: Tomohiro Ohkubo, Keita Kamiya, Masakazu Hara, Tomoka Yokoyama
المصدر: Archives of Biochemistry and Biophysics. 691:108510
مصطلحات موضوعية: 0301 basic medicine, Circular dichroism, Hydrophobicity, Mutant, Arabidopsis, Biophysics, Dehydrin, Intrinsically disordered proteins, Biochemistry, 03 medical and health sciences, chemistry.chemical_compound, Cryoprotective Agents, Freezing, Amino Acid Sequence, Amino Acids, Sodium dodecyl sulfate, Molecular Biology, chemistry.chemical_classification, L-Lactate Dehydrogenase, 030102 biochemistry & molecular biology, biology, Arabidopsis Proteins, Chemistry, Late embryogenesis abundant (LEA) proteins, biology.organism_classification, Cryoprotection, Amino acid, 030104 developmental biology, Enzyme, Mutation, Ultracentrifuge, Hydrophobic and Hydrophilic Interactions, Cold stress
الوصف: Dehydrins are intrinsically disordered proteins which are related to cold tolerance in plants. Dehydrins show potent cryoprotective activities for freeze-sensitive enzymes such as lactate dehydrogenase (LDH). Previous studies demonstrated that K-segments conserved in dehydrins had cryoprotective activities and that K-segment activities depended on the hydrophobic amino acids in the segment. However, the cryoprotective roles of hydrophobic amino acids in dehydrin itself have not been reported. Here, we demonstrated that hydrophobic amino acids were required for the cryoprotective activity of Arabidopsis dehydrin AtHIRD11. Cryoprotective activities were compared between AtHIRD11 and the corresponding mutant in which all hydrophobic residues were changed to T (AtHIRD11Φ/T) by using LDH. The change strikingly reduced AtHIRD11 activity. A segmentation analysis indicated that the conserved K-segment (Kseg) and a previously unidentified segment (non-K-segment 1, NK1) showed cryoprotective activities. Circular dichroism indicated that the secondary structures of all peptides showed disorder, but only cryoprotective peptides changed to the ordered forms by sodium dodecyl sulfate. Ultracentrifuge analysis indicated that AtHIRD11 and AtHIRD11Φ/T had similar molecular sizes in solution. These results suggest that not only structural disorder but also hydrophobic amino acids contributed to the cryoprotective activity of AtHIRD11. A possible mechanism based on an extended molecular shield model is proposed.
وصف الملف: application/pdf
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::4f86c401ec10e8c618f28305b21dd1f5Test
https://doi.org/10.1016/j.abb.2020.108510Test -
2
المصدر: Archives of biochemistry and biophysics. 390(2)
مصطلحات موضوعية: Euglena gracilis, Stereochemistry, ved/biology.organism_classification_rank.species, Biophysics, Respiratory chain, Biochemistry, Euglena, Binding, Competitive, chemistry.chemical_compound, Cytochrome b2, Lactate dehydrogenase, Enzyme Stability, Animals, Lactic Acid, Molecular Biology, Lactate Dehydrogenases, biology, L-Lactate Dehydrogenase, ved/biology, Active site, Membrane Proteins, Biological Transport, Stereoisomerism, biology.organism_classification, Mersalyl, Mitochondria, Molecular Weight, Kinetics, chemistry, Solubility, D-lactate dehydrogenase, biology.protein, L-Lactate Dehydrogenase (Cytochrome)
الوصف: The activity of the pyridine nucleotide-independent lactate dehydrogenase (iLDH) was characterized in mitochondria isolated from the protist Euglena gracilis. The dissociation constants for L- and D-lactate were similar, but the V(max) was higher with the d isomer. A ping-pong kinetic mechanism was displayed with 2,4-dichlorophenol-indolphenol (DCPIP), or coenzyme Q(1), reacting as the second substrate with the modified, reduced enzyme. Oxamate was a competitive inhibitor against both L- and D-lactate. Oxalate exerted a mixed-type inhibition regarding L- or D-lactate and also against DCPIP. The rate of L-lactate uptake was partially inhibited by mersalyl and lower than the rate of dehydrogenation, which was mersalyl-insensitive. These data suggested that the active site of L-iLDH was orientated toward the intermembrane space. The following observations indicated the existence of two stereo-specific iLDH enzymes in the inner membrane of Euglena mitochondria: a greater affinity of the D-iLDH for both inhibitors, D-iLDH thermo-stability at 70 degrees C and denaturation of L-iLDH, opposite signs in the enthalpy change for the association reaction of the isomers to the enzyme, differential solubilization of both activities with detergents, and different molecular mass.
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::4292ae9aaed90caf4cc35d46d697288aTest
https://pubmed.ncbi.nlm.nih.gov/11396932Test -
3
المؤلفون: Margaret L. Fonda, Robert W. Cuddihee
المصدر: Archives of Biochemistry and Biophysics. 212:705-716
مصطلحات موضوعية: Biophysics, Analytical chemistry, Models, Biological, Biochemistry, Degree (temperature), chemistry.chemical_compound, symbols.namesake, Eptesicus fuscus, Chiroptera, Lactate dehydrogenase, Animals, Molecular Biology, Arrhenius equation, L-Lactate Dehydrogenase, biology, Chemistry, Myocardium, Temperature, Substrate (chemistry), biology.organism_classification, Substrate concentration, Isoenzymes, Kinetics, Liver, symbols, NAD+ kinase, Ldh activity, Mathematics
الوصف: The effect of temperature on the activities of M4 and H4 lactate dehydrogenases (LDH, EC 1.1.1.27) isolated from the big brown bat (Eptesicus fuscus) was examined. Temperature effects were dependent on the concentrations of all four LDH substrates, pyruvate, lactate, NADH, and NAD. Arrhenius plots of In vi vs reciprocal of absolute temperature were linear for all but the lowest substrate concentrations. The slopes of these Arrhenius plots were used to calculate the temperature effect parameter (μ). Substrate-dependent temperature effects for M4 and H4 LDH were described by an equation for a rectangular hyperbola, μ = [E β S + E α K t ] [K t + S] proposed by G. R. Harbison and J. R. Fisher (1974, Comp. Biochem. Physiol.47B, 27–32) for adenosine deaminase. The parameters Eα (μ at infinitely low substrate concentration), Eβ (μ at infinitely high substrate concentration), and Kt (the concentration of substrate when μ = [E α + E β ] 2 ) can be used to describe the temperature dependence of LDH activity at any substrate concentration and to compare the substrate-dependent temperature effects on the two isoenzymes. Significantly different Eβ and Kt values for pyruvate-dependent temperature effects and different Eβ, Eα, Kt, and Eβ − Eα (the range of possible μ values) for lactate-dependent temperature effects were found between M4 and H4 LDH isoenzymes. High lactate concentrations inhibited bat H4 LDH activity to a greater degree at low temperatures than at high temperatures. Thus substrate inhibition plays an important role in the effect of temperature on the activity of H-type LDH at high lactate concentrations. Substrate-dependent temperature effects on bat LDH activity were the result of temperature effects on the apparent Km value of the respective substrate. Since both the apparent Km for pyruvate and the Ki for the competitive inhibitor oxamate decreased with decreasing temperature, the substrate-dependent temperature effects observed for pyruvate probably resulted from an increased affinity between pyruvate and the LDH-NADH complex with decreasing temperature.
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::07a7d65e751812642496faaaf4640286Test
https://doi.org/10.1016/0003-9861Test(81)90415-x -
4
المؤلفون: Nathan O. Kaplan, Ronald D. Eichner
المصدر: Archives of Biochemistry and Biophysics. 181:490-500
مصطلحات موضوعية: Tail, Immunodiffusion, Protein Conformation, Electrophoresis, Starch Gel, Biophysics, Biochemistry, Antigen-Antibody Reactions, chemistry.chemical_compound, Protein structure, Tetramer, Lactate dehydrogenase, Animals, Cysteine, Amino Acids, Molecular Biology, chemistry.chemical_classification, Homarus, L-Lactate Dehydrogenase, biology, Molecular mass, Osmolar Concentration, Extremities, Complement System Proteins, biology.organism_classification, Nephropidae, Isoenzymes, Molecular Weight, Enzyme, chemistry, Ionic strength, Ultracentrifuge, Ultracentrifugation
الوصف: Two isoenzymes of lactate dehydrogenase have been purified from Homarus americanus: One is found predominantly in the tail muscles; the other, in the walking leg muscles. This is the first demonstration of multiple forms of l -specific lactate dehydrogenase in an invertebrate organism. These proteins contain four essential sulfhydryl groups titratable by p -hydroxymercuribenzoate and 5,5′-dithiobis(2-nitrobenzoic acid). The molecular weights of these isoenzymes are dependent upon ionic strength. The native tetramer ( M r 145,000) exists in low ionic strength solutions; the active dimer ( M r 75,000), in high ionic strength solutions; this is the only example of lactate dehydrogenase disaggregation without concomitant loss in enzymatic activity. Microcomplement fixation studies suggest that there may be less than 4% difference in the primary structures of these two proteins.
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::da53a913d193464e6833f941a5ce302fTest
https://doi.org/10.1016/0003-9861Test(77)90255-7 -
5
المؤلفون: J.S. Clegg, R.D. Ewing
المصدر: Archives of Biochemistry and Biophysics. 150:566-572
مصطلحات موضوعية: Electrophoresis, Embryo, Nonmammalian, Starch, Electrophoresis, Starch Gel, Biophysics, Brine shrimp, Biochemistry, Oxalate, chemistry.chemical_compound, Decapoda, Lactate dehydrogenase, Animals, Pyruvates, Molecular Biology, Polyacrylamide gel electrophoresis, chemistry.chemical_classification, Oxalates, L-Lactate Dehydrogenase, biology, NAD, biology.organism_classification, Keto Acids, Cellulose acetate, Molecular Weight, Butyrates, Kinetics, Enzyme, chemistry, Spectrophotometry, Larva, Chromatography, Gel, Lactates, Artemia salina, Ultracentrifugation
الوصف: A study of lactate dehydrogenase in encysted embryos, nauplii (larvae) and adults of the brine shrimp, Artemia salina , indicates that this enzyme, specific for l -lactate exists in a single macromolecular form throughout the life cycle. A single band of activity was observed in all Artemia extracts by polyacrylamide gel, starch gel, and cellulose acetate strip electrophoresis, under a variety of experimental conditions. Lactate dehydrogenase activities from different stages of the life cycle showed similar responses to pyruvate and lactate concentrations, utilization of α-ketobutyrate, and inhibition by oxalate. The molecular weight was estimated to be between 140,000 and 150,000.
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::799dd369f52594a028743de2453788f4Test
https://doi.org/10.1016/0003-9861Test(72)90075-6 -
6
المؤلفون: Malathy Singh, B.L. Horecker, J.T. August, Vishwa Nath Singh
المصدر: Archives of Biochemistry and Biophysics. 165:240-246
مصطلحات موضوعية: chemistry.chemical_classification, Rous sarcoma virus, Hexokinase, animal structures, Biophysics, Dehydrogenase, Biology, biology.organism_classification, Biochemistry, Molecular biology, chemistry.chemical_compound, Enzyme, chemistry, Lactate dehydrogenase, embryonic structures, Glycolysis, Molecular Biology, Pyruvate kinase, Phosphofructokinase
الوصف: Effects of transformation by Rous sarcoma virus of Schmidt-Ruppin strain on the activities of key enzymes of the glycolytic and the hexose monophosphate shunt pathways in chick-embryo cells were investigated. Activities of hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase, and glucose-6- P dehydrogenase were increased about twofold in the transformed cells, but that of 6- P -gluconate dehydrogenase remained unaltered. The transformation-mediated increase in the activity of hexokinase was confined entirely to the bound form of the enzyme. Cells infected with a temperature-sensitive mutant (Ts-68) of Schmidt-Ruppin strain of Rous sarcoma virus showed the typical increase in the rate of 2-deoxyglucose uptake and the activities of hexokinase, phosphofructokinase, pyruvate kinase, and glucose-6- P dehydrogenase at the permissive temperature (37 °C), but when the infected cells were grown at the nonpermissive temperature (41 °C), the increases in the sugar uptake and activities of these enzymes were abolished. Unlike the regulatory enzymes, lactate dehydrogenase activity was increased at both the permissive and the nonpermissive temperatures.
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::f9f48ef1df16f7cecaaaef99a6d9f52bTest
https://doi.org/10.1016/0003-9861Test(74)90160-x -
7
المؤلفون: A.K. Ghosh, E.K. Pye, Britton Chance
المصدر: Archives of Biochemistry and Biophysics. 145:319-331
مصطلحات موضوعية: Azides, Periodicity, Population, Biophysics, Antimycin A, Acetaldehyde, Biology, Models, Biological, Biochemistry, Saccharomyces, chemistry.chemical_compound, Chlorides, Oscillometry, Extracellular, Fluorometry, Magnesium, education, Molecular Biology, Glycolytic oscillation, education.field_of_study, Cyanides, L-Lactate Dehydrogenase, Oscillation, Sodium, Hydrogen-Ion Concentration, NAD, biology.organism_classification, Yeast, Semicarbazides, Alcohol Oxidoreductases, Glucose, chemistry, Potassium, Glycolysis
الوصف: The regular appearance of large NADH oscillations in mixtures of equal amounts of two suspensions of S. carlsbergensis originally oscillating approximately 180 ° out of phase is highly suggestive of the existence of an extracellular synchronizer of the glycolytic oscillation in this yeast. Two types of synchronization are usually observed: (a) both the phase and frequency of the mixed population oscillation are synchronized with one of the parent populations and (b) the frequency only is synchronized, i.e., the phase of the oscillation in the mixture is not close to either of the two parent suspensions. The large number of sustained oscillations at higher pH as compared to pH 4.5 suggests the possibility that damping may be due to a desynchronization process which is less effective at higher pH. In the absence of aldehyde traps such as KCN, Girard's reagent P, semicarbazide, or a mixture of NADH and ADH, the oscillations in the mixed suspension are highly damped and the frequency changes continuously. This suggests that acetaldehyde, secreted by the cells, may have a role as a desynchronizer of the oscillations. Mg2+ ion has the property of increasing the frequency of NADH oscillations in S. carlsbergensis. The synchronization of metabolism between individual yeast cells, which is described here, may be important as an example of a phenomenon common to many different cell types.
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::79dce1b97ff54a0d99b7cb332005b09bTest
https://doi.org/10.1016/0003-9861Test(71)90042-7 -
8
المؤلفون: Nathan O. Kaplan, George L. Long
المصدر: Archives of Biochemistry and Biophysics. 154:696-710
مصطلحات موضوعية: chemistry.chemical_classification, Molecular mass, Biophysics, Dehydrogenase, Biology, biology.organism_classification, Biochemistry, Cofactor, Turnover number, Horseshoe crab, chemistry.chemical_compound, Enzyme, chemistry, Sephadex, Limulus, Lactate dehydrogenase, Iodoacetamide, biology.protein, Coenzyme binding, NAD+ kinase, Molecular Biology
الوصف: The catalytic properties of the purified horseshoe crab and seaworm d -lactate dehydrogenases were determined and compared with those of several l -lactate dehydrogenases. Apparent Km's and degrees of substrate inhibition have been determined for both enzymes for pyruvate, d -lactate, NAD+ and NADH. They are similar to those found for l -lactate dehydrogenases. The Limulus “muscle”-type lactate dehydrogenase is notably different from the “heart”-type lactate dehydrogenase of this organism in a number of properties. The Limulus heart and muscle enzymes have been shown by several criteria to be stereospecific for d -lactate. They also stereospecifically transfer the 4-α hydrogen of NADH to pyruvate. The turnover number for purified Limulus muscle lactate dehydrogenase is 38,000 moles NADH oxidized per mole of enzyme, per minute. Limulus and Nereis lactate dehydrogenases are inhibited by oxamate and the reduced NAD-pyruvate adduct. Limulus muscle lactate dehydrogenase is stoichiometrically inhibited by para-hydroxymercuribenzoate. Extrapolation to two moles parahydroxymercuribenzoate bound to one mole of enzyme yields 100% inhibition. Alkylation by iodoacetamide or iodoacetate occurs even in the absence of urea or guanidine-HCl. Evidence suggests that the reactive sulfhydryl group may not be located at the coenzyme binding site. Reduced coenzyme (NADH or the 3-acetyl-pyridine analogue of NADH) stoichiometrically binds to Limulus muscle lactate dehydrogenase (two moles per mole of enzyme). Several pieces of physical and catalytic evidence suggest that the d - and l -lactate dehydrogenase are products of homologous genes. A consideration of a possible “active site” shows that as few as one or two key conservative amino acid changes could lead to a reversal of the lactate stereospecificity.
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::25e4126b5d4ee33390b872a1ca50788eTest
https://doi.org/10.1016/0003-9861Test(73)90025-8 -
9
المؤلفون: W.Ross Ellington, George Louis Long, James R. Cook
المصدر: Archives of biochemistry and biophysics. 191(1)
مصطلحات موضوعية: Stereochemistry, NADH binding, Biophysics, chemistry.chemical_element, Zinc, Balanus nubilus, Biochemistry, Metal Chelator, chemistry.chemical_compound, Structure-Activity Relationship, Lactate dehydrogenase, Coenzyme binding, Animals, Chelation, Molecular Biology, Edetic Acid, biology, L-Lactate Dehydrogenase, Thoracica, biology.organism_classification, Kinetics, chemistry, D-lactate dehydrogenase, Quinolines, Phenanthrolines
الوصف: Purified NAD-linked d -lactate dehydrogenase from the depressor muscle of the giant barnacle, Balanus nubilus Darwin, is inactivated when incubated with the metal chelators o-phenanthroline and EDTA. M-Phenanthroline and p-phenanthroline, which lack metal chelating ability, are ineffective in inactivating the enzyme. Inactivated enzyme can be reactivated by the addition of zinc ions to the assay mixture. Atomic absorption spectrophotometric analysis of purified B. nubilus d -lactate dehydrogenase revealed that this enzyme contains stoichiometric amounts of zinc (2 g-atoms per mol of subunit), unlike other lactate dehydrogenases, which lack zinc. Zinc appears to be required for maximal catalytic activity. Aromatic, nitrogen-containing metal chelators and their nonchelating analogs are effective instantaneous inhibitors of B. nubilus d -lactate dehydrogenase. These compounds bind at the coenzyme binding site, as the mode of inhibition is distinctly competitive with respect to NADH. The different effects of metal chelators and their nonchelator analogs suggest that time-dependent inactivation (chelation of the enzyme zinc ions) and instantaneous inhibition (competition with NADH binding) have independent mechanisms.
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::063b0f983ba4593325d2d4558f56e7acTest
https://pubmed.ncbi.nlm.nih.gov/104663Test -
10
المؤلفون: Nathan O. Kaplan, Ronald D. Eichner
المصدر: Archives of biochemistry and biophysics. 191(2)
مصطلحات موضوعية: Stereochemistry, Dimer, Biophysics, Ionic bonding, Biochemistry, chemistry.chemical_compound, Lactate dehydrogenase, Animals, Molecular Biology, chemistry.chemical_classification, Homarus, biology, L-Lactate Dehydrogenase, Muscles, Osmolar Concentration, biology.organism_classification, NAD, Lactic acid, Nephropidae, Kinetics, Enzyme, chemistry, Ionic strength, Lactates, NAD+ kinase, Oxidation-Reduction
الوصف: The mechanism of lactic acid oxidation in the tail muscles of Homarus americanus was studied. In solutions of intermediate ionic strength (0.55) time-course progress curves for lactic acid oxidation as catalyzed by lactate dehydrogenase exhibited a lag period. Evidence is presented which indicates that the lactate dehydrogenase found in the tail muscles of the lobster exists in two distinct physical and kinetic forms. The equilibrium of these forms is dependent upon the ionic strength of the reaction mixture. In low ionic strength solutions, the enzyme exists as a tetrameric species with an apparent Km for lactic acid of 1.1 m ; in high ionic strength solutions, the enzyme exists as a dimer and the corresponding Km is 0.028 m . At intermediate ionic strengths, an equilibrium between the two physical and kinetic species exists which is modulated by the NADH mole-fraction ( [ NADH ] [ NADH + NAD + ] ) and, in turn, this modulation results in sigmoidal time-course progress curves. The role of this enzyme is discussed as affected by in vivo ionic strength, temperature and levels of oxidized and reduced nicotine adenine dinucleotides.
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::b1b27e29d5df04e88fc22769facfc98cTest
https://pubmed.ncbi.nlm.nih.gov/217308Test
