Non-thermal Effects of a Ceramics Radiation on Reversibility of Lactate Dehydrogenase Reaction

1996 ◽  
Vol 60 (2) ◽  
pp. 284-287 ◽  
Author(s):  
Masahiro Kohashi ◽  
Yuko Kasuya ◽  
Tatsuo Watanabe
Keyword(s):  
Lactate Dehydrogenase ◽  
Thermal Effects ◽  
Dehydrogenase Reaction

The A245K Mutation Exposes Another Stage of the Bacteriall-Lactate Dehydrogenase Reaction Mechanism†

Biochemistry ◽  
2001 ◽  
Vol 40 (24) ◽  
pp. 7247-7252 ◽  
Author(s):  
Paweł Kȩdzierski ◽  
Kathleen Moreton ◽  
Antony R. Clarke ◽  
J. John Holbrook
Keyword(s):  
Reaction Mechanism ◽  
Lactate Dehydrogenase ◽  
Dehydrogenase Reaction

Cytosolic NADH redox and thiol oxidation regulate pulmonary arterial force through ERK MAP kinase

2005 ◽  
Vol 288 (6) ◽  
pp. L1017-L1025 ◽  
Author(s):  
Richard A. Oeckler ◽  
Elizabeth Arcuino ◽  
Mansoor Ahmad ◽  
Susan C. Olson ◽  
Michael S. Wolin
Keyword(s):  
Lactate Dehydrogenase ◽  
Map Kinase ◽  
Pulmonary Arteries ◽  
Force Generation ◽  
Thiol Oxidation ◽  
Erk Activation ◽  
Contractile Mechanism ◽  
Erk Phosphorylation ◽  
Dehydrogenase Reaction ◽  
Pulmonary Arterial

An ERK MAP kinase-mediated contractile mechanism previously reported to be activated by peroxide and stretch in bovine coronary arteries is shown in this study to be present in endothelium-denuded bovine pulmonary arteries and subject to regulation by modulation of cytosolic NAD(H) redox through the lactate dehydrogenase reaction. Although our previous work identified an acute Po2-dependent peroxide-mediated relaxation of bovine pulmonary arteries on exposure to lactate, a 30-min treatment with 10 mM lactate enhanced ERK phosphorylation and increased force generation to 30 mM KCl. Hypoxia inhibited these responses to lactate. Increases in ERK phosphorylation and the enhancement of force generation by lactate and stretch are attenuated in the presence of inhibitors of Nox oxidase (0.1 mM apocynin) or ERK activation (10 μM PD-98059) and by 0.1 mM ebselen. Additionally, incubation of pulmonary arteries with 10 mM pyruvate lowered basal levels of ERK phosphorylation, and it inhibited both the ERK phosphorylation and the enhancement in force generation to 30 mM KCl caused by stretch. Treatment of pulmonary arteries with the thiol oxidant diamide (1 μM) elicited what appears to be a peroxide-independent increase in force and ERK phosphorylation that were both attenuated by PD-98059. Thus pulmonary arteries possess a peroxide-elicited contractile mechanism involving ERK MAP kinase, which is stimulated by stretch and regulated through the control of Nox oxidase activity by the availability of cytosolic NADH.

scholarly journals The lactate dehydrogenase–reduced nicotinamide–adenine dinucleotide–pyruvate complex. Kinetics of pyruvate binding and quenching of coenzyme fluorescence

1974 ◽  
Vol 139 (1) ◽  
pp. 251-259 ◽  
Author(s):  
J. Südi
Keyword(s):  
Lactate Dehydrogenase ◽  
Rate Constants ◽  
Kinetic Studies ◽  
Reduction Reaction ◽  
Reverse Direction ◽  
Total Change ◽  
Sequential Reaction ◽  
Oxidation Reduction ◽  
Dehydrogenase Reaction ◽  
Absorbing Material

The stopped-flow kinetic studies described in this and the following paper (Südi, 1974) demonstrate that a Haldane-type description of the reversible lactate dehydrogenase reaction presents an experimentally feasible task. Combined results of these two papers yield numerical values for the six rate constants defined by the following equilibrium scheme, where E represents lactate dehydrogenase: [Formula: see text] The experiments were carried out at pH8.4 at a relatively low temperature (6.3°C) with the pig heart enzyme. Identification of the above two intermediates and determination of the corresponding rate constants actually involve four series of independent observations in these studies, since (a) the reaction can be followed in both directions, and (b) both the u.v. absorption and the fluorescence of the coenzymes are altered in the reaction, and it is shown that these two spectral changes do not occur simultaneously. Kinetic observations made in the reverse direction are reported in this paper. It is demonstrated that the fluorescence of NADH can no longer be observed in the ternary complex ENADHPyr. Even though the oxidation–reduction reaction rapidly follows the formation of this complex, the numerical values of k−4 (8.33×105m−1·s−1) and k+4 (222s−1) are easily obtained from a directly observed second-order reaction step in which fluorescent but not u.v.-absorbing material is disappearing. U.v.-absorption measurements do not clearly resolve the subsequent oxidation–reduction step from the dissociation of lactate. It is shown that this must be due partly to the instrumental dead time, and partly to a low transient concentration of ENAD+Lac in the two-step sequential reaction in which the detectable disappearance of u.v.-absorbing material takes place. It is estimated that about one-tenth of the total change in u.v. absorption is due to a `burst reaction' in which ENAD+Lac is produced, and this estimation yields, from kobs.=120s−1, k−2=1200s−1.

scholarly journals The reversibility of cytosolic dehydrogenase reactions in hepatocytes from starved and fed rats. Effect of fructose

1984 ◽  
Vol 222 (2) ◽  
pp. 437-446 ◽  
Author(s):  
C Vind ◽  
N Grunnet
Keyword(s):  
Lactate Dehydrogenase ◽  
Alcohol Dehydrogenase ◽  
Ethanol Oxidation ◽  
Maximal Activity ◽  
Isolated Hepatocytes ◽  
Single Compartment ◽  
Dehydrogenase Reaction ◽  
Order Of Magnitude ◽  
Rate Limiting

The metabolism of [2-3H]lactate was studied in isolated hepatocytes from fed and starved rats metabolizing ethanol and lactate in the absence and presence of fructose. The yields of 3H in ethanol, water, glucose and glycerol were determined. The rate of ethanol oxidation (3 mumol/min per g wet wt.) was the same for fed and starved rats with and without fructose. From the detritiation of labelled lactate and the labelling pattern of ethanol and glucose, we calculated the rate of reoxidation of NADH catalysed by lactate dehydrogenase, alcohol dehydrogenase and triosephosphate dehydrogenase. The calculated flux of reducing equivalents from NADH to pyruvate was of the same order of magnitude as previously found with [3H]ethanol or [3H]xylitol as the labelled substrate [Vind & Grunnet (1982) Biochim. Biophys. Acta 720, 295-302]. The results suggest that the cytoplasm can be regarded as a single compartment with respect to NAD(H). The rate of reduction of acetaldehyde and pyruvate was correlated with the concentration of these metabolites and NADH, and was highest in fed rats and during fructose metabolism. The rate of reoxidation of NADH catalysed by lactate dehydrogenase was only a few per cent of the maximal activity of the enzymes, but the rate of reoxidation of NADH catalysed by alcohol dehydrogenase was equal to or higher than the maximal activity as measured in vitro, suggesting that the dissociation of enzyme-bound NAD+ as well as NADH may be rate-limiting steps in the alcohol dehydrogenase reaction.

Interactions among pyruvate concentration, pH, and Km of pyruvate in determining in vivo Q10 values of the lactate dehydrogenase reaction

1982 ◽  
Vol 60 (6) ◽  
pp. 1293-1299 ◽  
Author(s):  
Patrick J. Walsh ◽  
George N. Somero
Keyword(s):  
Lactate Dehydrogenase ◽  
Temperature Dependent ◽  
Temperature Changes ◽  
Gillichthys Mirabilis ◽  
Constant Ph ◽  
Dehydrogenase Reaction ◽  
Regulatory Capacity ◽  
Time Courses ◽  
Q10 Values

The interactions among pyruvate concentration, the apparent Michaelis constant (Km) of pyruvate, and intracellular pH on the Q10 of the lactate dehydrogenase (LDH) reaction of white skeletal muscle of the fish Gillichthys mirabilis were studied. Experimentally determined values for pyruvate concentration and Km of pyruvate (measured under both constant pH and variable (=biologically realistic) pH were used to estimate in vivo Q10's over acclimation time courses and in acute temperature-change situations. Temperature-dependent changes in pyruvate concentration were large. The 25 °C acclimated fish had approximately twice the pyruvate concentration of 15 °C acclimated specimens, and acute temperature changes also led to higher pyruvate levels at higher temperatures. These temperature-dependent changes in pyruvate concentration prevent temperature-dependent variation in the Km of pyruvate from having Q10-reducing influences. Rather, during acclimation a relatively stable ratio of Km: [substrate] is maintained. This is viewed as important for the preservation of correct regulatory capacity for the muscle LDH reaction.

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