Immunochemical approach to the question of inactive subunits in cases of lactate dehydrogenase B subunit deficiency.

1986 ◽  
Vol 32 (1) ◽  
pp. 116-119 ◽  
Author(s):  
M Maekawa ◽  
K Sudo ◽  
T Kanno

Abstract If there were enzymatically inactive B subunits in a solution containing lactate dehydrogenase (LD) B4 prepared from the hemolysates of heterozygous individuals with LD-B subunit deficiency, the inactive subunits would compete with normal subunits for antibodies to the B4 subunit. Using the activity of normal LD-B4 as an index, we could ascertain the proportion of free antigen (LD-B4) and antibody-antigen complexes (LD-B4-anti-LD-B4) and calculate the apparent equilibrium constant, Keq. Doing so, we found the value for Keq in LD-B subunit deficiency to be smaller than that for normal controls. Evidently the expected competitive reaction takes place. We conclude that heterozygous individuals with LD-B subunit deficiency do indeed produce variant (enzymatically inactive) B subunits of LD.

1977 ◽  
Vol 55 (8) ◽  
pp. 796-803 ◽  
Author(s):  
B. F. Peterman ◽  
R. A. Morton

The apparent equilibrium constant and rate of oxidation was investigated for the reaction of cytochrome c with iron hexacyanide. It was found that if horse heart ferricytochrome c was exposed to ferricyanide (to oxidize traces of reduced protein) the cytochrome subsequently, even after extensive dialysis, had an apparent equilibrium constant different from that of electrodialyzed protein. The effect of ferricyanide ion apparently cannot be removed by ordinary dialysis. The ionic strength dependence of the apparent equilibrium constant and bimolecular oxidation rate constant was measured in the range 1–200 mM using Tris–cacodylate or potassium phosphate buffers at pH 7.0, and electrodialyzed horse heart cytochrome c. The oxidation reaction proceeded very rapidly. Extrapolated to zero ionic strength, kox(~ 9 × 109 M−1 s−1) was about 7% of that calculated for a diffusion-limited reaction. Since the exposed heme edge occupies only the order of 3% of the surface area, electron transfer apparently results at nearly every collision with the active-site region. An effective charge of + 7.8 units was estimated for the oxidation reaction. The rate of oxidation of Pseudomonas aeruginosa c551 was much slower (kox at μ = 0 was the order of 6 × 103), and was not consistent with diffusion-limited kinetics.


1982 ◽  
Vol 47 (3) ◽  
pp. 736-743 ◽  
Author(s):  
Jan Balej ◽  
Otomar Špalek

The solubility of Na2O2.8 H2O in the multicomponent system H2O2-NaOH-KOH-H2O has been investigated at temperatures of 12, 20, and 30°C. Comparison of the data with solubilities of the same compound in the simler system H2O2-NaOH-H2) shows that the presence of potassium hydroxide increases the solubility at the same temperature and total content of hydroxide ions. The effect of potassium ions on the solubility of Na2O2.8 H2O is expressed by an empirical equation relating the apparent equilibrium constant of the dissolution reaction and the molalities of the perhydroxyl and potassium ions at a given temperature.


1990 ◽  
Vol 267 (3) ◽  
pp. 739-743 ◽  
Author(s):  
J E Lunn ◽  
T ap Rees

The aim of this work was to use preparations from germinating seeds of Pisum sativum to determine the apparent equilibrium constant of the reaction catalysed by sucrose-phosphate synthase (EC 2.4.1.14) and to compare this with the mass-action ratio of the reaction in the seeds. The apparent equilibrium constant ranged from 5.3 at 0.25 mM-MgCl2, pH 7.0, to 62 at 10 mM-MgCl2, pH 7.5. The sucrose phosphate content of the seeds, 23 nmol/g fresh wt., was determined by separating sucrose phosphate from sucrose by ion-exchange chromatography and then measuring the sucrose released by alkaline phosphatase. Comparison of equilibrium constants and mass-action ratios in the cotyledons of 38 h-germinated seeds showed that the reactions catalysed by glucose-6-phosphate isomerase, phosphoglucomutase and UDP-glucose pyrophosphorylase are close to equilibrium, and those catalysed by sucrose-phosphate synthase and sucrose phosphatase are considerably displaced from equilibrium in vivo.


1964 ◽  
Vol 42 (2) ◽  
pp. 403-415 ◽  
Author(s):  
George W. Kosicki ◽  
Stanislava N. Lipovac

Spectrophotometric studies of the spontaneous and magnesium-ion-catalyzed decarboxylation of oxalacetic acid in H2O and D2O have been carried out over a range of pH, pD, and magnesium ion concentrations.The rate of decarboxylation of oxalacetic acid depends on the proposed equilibrium system between the acid anion and magnesium chelate under a variety of conditions.The absorbancy indexes and the apparent equilibrium constant of the keto and enol forms of the magnesium chelate were estimated from a combination of the kinetic and spectral data.


1973 ◽  
Vol 51 (5) ◽  
pp. 556-559 ◽  
Author(s):  
Ronald W. McClard ◽  
Harold M. Kolenbrander

The effects of temperature on the energy of activation, the enthalpy of binding, and the apparent equilibrium constant for the overall reaction catalyzed by L-histidine ammonia-lyase (EC 4.3.1.3) have been determined. A temperature-dependent transition (at approximately 30°) involving multiple forms of the enzyme is also discussed.The enthalpy of binding is exothermic above 30° and endothermic below this transition temperature. In addition, a bend is observed in the Arrhenius plots at approximately 34°. The combination of these effects suggests the existence of at least two forms of the enzyme.


1982 ◽  
Vol 205 (2) ◽  
pp. 313-320 ◽  
Author(s):  
T J Beebee ◽  
D S Carty

We have developed procedures for purifying lactate dehydrogenase isoenzymes from rat tissues that involve two affinity-chromatography steps and that facilitate the isolation of milligram quantities of highly purified proteins within 2-3 days. Antibodies raised against pure A and B subunits in rabbits and hens were used in radioimmunoassays and showed negligible cross-reactivity with heterologous subunits. The radioimmunoassays provide a sensitive method for measuring nanogram amounts of A-subunit and B-subunit polypeptides in tissue homogenates and were employed to characterize the enzyme purification procedures.


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