scholarly journals Aspartate aminotransferase. The effects of ionic concentration on kinetic constants of both isoenzymes

1968 ◽  
Vol 106 (3) ◽  
pp. 581-586 ◽  
Author(s):  
T. R. C. Boyde
Keyword(s):  
Aspartate Aminotransferase ◽  
Specific Effect ◽  
Ionic Concentration ◽  
Phosphate Concentration ◽  
Kinetic Constants ◽  
Sharp Minimum ◽  
Ionic Concentrations ◽  
Michaelis Constants ◽  
Added Salt

1. The Michaelis constants for both isoenzymes for both substrates depend strongly on ionic concentration, being approximately proportional to phosphate concentration over considerable ranges. This is probably an effect of anions only. 2. In the absence of added salt, Km (2-oxoglutarate) (anionic isoenzyme) is so small as to be indeterminate. 3. Km (l-aspartate) (anionic isoenzyme) passes through a sharp minimum at about 3·3mm-phosphate. It is not clear whether this is a specific effect of phosphate. 4. Both substrates are inhibitory at sufficiently low ionic concentrations. 5. A modified graphical procedure is described for the derivation of the kinetic constants.

scholarly journals Characteristics of ionic concentration and δ18O and their variability in dry-season and wet-season snow on Ürümqi glacier No. 1, eastern Tien Shan, central Asia

2008 ◽  
Vol 49 ◽  
pp. 217-223 ◽  
Author(s):  
Zhongqin Li ◽  
Wenbin Wang ◽  
Feiteng Wang ◽  
Huilin Li ◽  
Mingjun Zhang
Keyword(s):  
Central Asia ◽  
Ionic Concentration ◽  
Tien Shan ◽  
Wet Season ◽  
Snow Chemistry ◽  
Ionic Concentrations ◽  
Depositional Processes ◽  
Surface Snow ◽  
Dry Seasons ◽  
Snow Samples

AbstractTo investigate the environmental and climatic significance of the ice-core records from the Tien Shan, central Asia, the characteristics of ionic concentration and oxygen isotopic ratio (δ18O) as well as their variability are assessed from surface-snow samples as well as old-snow samples collected year-round at weekly intervals from November 2002 to October 2005 on Ürümqi glacier No. 1, eastern Tien Shan. The results indicate that the δ18O in surface-snow samples is reversely coincident with air temperature and insignificantly affected by post-depositional processes. Ionic concentrations in the wet-season (1 November to 31 March) snow are overall higher than those in dry-season (1 April to 31 October) snow, while the variability of relative ionic composition between dry seasons is slightly less than that between wet seasons. During dry seasons, surface-snow chemistry was mostly controlled by the chemical content entrained in some sporadic precipitations. When precipitation is absent, the effect of all post-depositional processes together elevated the ionic concentrations in surface snow. During wet seasons, the snow chemistry is determined mainly by the input of aerosols entrained in precipitation and the elution process from percolation of meltwater.

scholarly journals Insight into Debye Hückel length (κ−1): smart gravimetric and swelling techniques reveals discrepancy of diffuse double layer theory at high ionic concentrations

2021 ◽  
Author(s):  
Talal AL-Bazali
Keyword(s):  
Layer Thickness ◽  
Double Layer ◽  
Critical Concentration ◽  
Ionic Concentration ◽  
Diffuse Double Layer ◽  
Ionic Concentrations ◽  
Osmotic Water ◽  
Ionic Valence ◽  
High Concentrations ◽  
Double Layer Thickness

AbstractSmart gravimetric and swelling techniques were utilized in this work to examine the validity of the Debye Hückel length (κ−1) equation when shale interacts with highly concentrated salt solutions. The swelling and shrinkage behavior of two different shales, when exposed to monovalent and divalent ionic solutions (NaCl, KCl and CaCl2) at concentrations ranging from 2 to 22%w/w was observed and measured. Shale swelling and shrinkage results show that Debye Hückel length (κ−1) equation seems to work adequately at low ionic concentrations where osmotic water flow out of shale plays a major role in decreasing the diffuse double layer thickness by withdrawing water out and thereby shrinking κ−1. At high ionic concentration levels, the flow of associated water into the diffuse double layer negates the withdrawal of osmotic water out of the diffuse double layer which could maintain κ−1 or possibly increase it. Data on measured ionic uptake into shale suggests that excessive ionic diffusion into shale, especially at high concentrations, leads to higher electrical repulsion between alike ions in the diffuse layer which could lead to the expansion of the diffuse double layer thickness. Furthermore, swelling and shrinkage data analysis for shale suggests the existence of a ‘critical concentration’ below which the Debye Hückel length equation works. Above the critical concentration, the validity of the Debye Hückel length equation might be in question. The critical concentration is different for all ions and depends on ionic valence, hydrated ion diameter, and clay type.

Kinetic studies of mutant human erythrocyte adenine phosphoribosyltransferases

1968 ◽  
Vol 46 (7) ◽  
pp. 703-706 ◽  
Author(s):  
J. Frank Henderson ◽  
Helen R. Miller ◽  
William N. Kelley ◽  
Frederick M. Rosenbloom ◽  
J. Edwin Seegmiller
Keyword(s):  
Reaction Mechanism ◽  
Human Erythrocyte ◽  
Enzyme Activities ◽  
Kinetic Studies ◽  
Kinetic Constants ◽  
Heat Inactivation ◽  
Adenine Phosphoribosyltransferase ◽  
Michaelis Constants ◽  
Low Degrees ◽  
Reduced Activity

The kinetic constants and reaction mechanism of human erythrocyte adenine phosphoribosyltransferase from individuals whose enzyme activities have high, intermediate, or low degrees of stability to heat inactivation, and in a human mutant with reduced activity of this enzyme, have been measured. The Michaelis constants for one or both substrates are different from normal in seven mutants.

scholarly journals Hydroponic lettuce production in different concentrations and flow rates of nutrient solution

2012 ◽  
Vol 30 (3) ◽  
pp. 526-530 ◽  
Author(s):  
Gláucio da C Genuncio ◽  
Marcelle Gomes ◽  
Anderson Claiton Ferrari ◽  
Nidia Majerowicz ◽  
Everaldo Zonta
Keyword(s):  
Nutrient Solution ◽  
Flow Rate ◽  
Aerial Part ◽  
Ionic Concentration ◽  
General Analysis ◽  
Ion Concentration ◽  
Fresh Weight ◽  
Flow Rates ◽  
Hydroponic System ◽  
Ionic Concentrations

The objective of this study was to evaluate the accumulation of fresh weight of hydroponic lettuce in terms of ionic concentrations and flow rates of nutrient solution. This work consisted of three experiments in NFT hydroponic system, conducted between July and September 2006. Lettuce cultivars Lucy Brown, Izabela and Veneza were grown in different ionic concentrations of the 100, 75 and 50% and flow rates of 1.50, 1.00 and 0.75 L min-1. Fresh weight gains were observed for Lucy Brown when grown on 100% of the ion concentration and a flow rate of nutrient solution of 1.0 L min-1. Greater fresh mass was observed for cvs. Izabela and Veneza under the flow rate of 1.5 L min-1. A general analysis of the data allows us to conclude that the application of nutrient solution at a flow rate of 1.5 L min-1, as well as 100% of the ionic concentration is effective to increase the fresh weight of the aerial part of cvs. Lucy Brown, Izabela and Veneza when grown in hydroponics.

scholarly journals Plasma concentration, kinetic constants, and gene polymorphism of angiotensin I-converting enzyme in centenarians

1998 ◽  
Vol 44 (10) ◽  
pp. 2083-2087 ◽  
Author(s):  
Laurence Faure-Delanef ◽  
Bruno Baudin ◽  
Bénédicte Bénéteau-Burnat ◽  
Jean-Christophe Beaudoin ◽  
Jacqueline Giboudeau ◽  
...  
Keyword(s):  
Kinetic Constants ◽  
Converting Enzyme ◽  
Angiotensin I ◽  
Cardiovascular Pathology ◽  
Angiotensin I Converting Enzyme ◽  
Its Gene ◽  
Causes Of Mortality ◽  
Michaelis Constants ◽  
Ace Activity ◽  
Optimal Ph

Abstract We have determined serum activity and kinetic constants of angiotensin I-converting enzyme (ACE), parallel to an insertion/deletion (I/D) polymorphism in its gene, in French centenarians and controls 20–70 years of age because this enzyme could have an impact on cardiovascular risk, and thus on longevity. Both the ACE D allele and ACE D/D genotype were more frequent in centenarians in comparison with controls, without sex-related differences nor significant correlation with a cardiovascular pathology. In centenarians, I/D polymorphism was correlated with circulating ACE activity (D/D genotype, 89.0 ± 36.8 U/L; I/D genotype, 63.5 ± 26.0 U/L; and I/I genotype, 55.1 ± 39.4 U/L). The Michaelis constants for two substrates were identical whatever the genotype and were not different between centenarians and controls, i.e., 0.30 ± 0.03 mmol/L for furylacryloyl-phenylalanyl-glycyl-glycine and 1.35 ± 0.05 mmol/L for hippuryl-histidyl-leucine; for the latter, the optimal pH and activating concentration of chloride did not depend on I/D polymorphism. The maximal velocities with both substrates reflected the distribution of serum ACE activity as a function of the genotypes, in centenarians and in controls. In conclusion, plasma ACE activity is subject to a similar genotypic influence in centenarians as in adults 20–70 years of age; however, ACE itself appears to be functionally similar for each genotype. Furthermore, the D allele as well as the higher serum ACE activities associated with the D/D genotype cannot discriminate individuals at high risk for cardiovascular diseases, major causes of mortality before the age of 100 years.

scholarly journals Determination of the mechanism and kinetic constants for hog kidney γ-glutamyltransferase

1976 ◽  
Vol 157 (3) ◽  
pp. 609-617 ◽  
Author(s):  
J W London ◽  
L M Shaw ◽  
D Fetterolf ◽  
D Garfinkel
Keyword(s):  
Initial Velocity ◽  
Competitive Inhibition ◽  
Linear Regression Analysis ◽  
Kinetic Constants ◽  
Reaction Products ◽  
Gamma Glutamyl ◽  
Ping Pong ◽  
Donor Acceptor ◽  
Michaelis Constants ◽  
Hog Kidney

The initial-velocity kinetics of hog kidney gamma-glutamyltransferase were studied. Glutamate gamma-(4-nitroanilide) and its 3-carboxy derivative, glutamate gamma-(3-carboxy-4-nitroanilide), served as gamma-glutamyl donors, and glycylglycine as an acceptor. Reaction products were identified by paper chromatography and amino acid analysis. Inhibited Ping Pong mechanisms and a comprehensive initial- velocity expression were developed which account for the observed simultaneous gamma-glutamyl transfer and autotransfer, competitive inhibition by glycylglycine, and non-competitive inhibition by the carboxy donor. The validity of the proposed Ping Pong mechanisms are supported by enzyme-velocity data obtained with constant ratios of acceptor to donor concentrations. Kinetic constants were determined by a non-linear regression analysis. With glutamate gamma-(4-nitroanilide) as the donor, Michaelis constants for the donor, acceptor and donor-acting-as-acceptor are 1.87, 24.9, and 2.08 mM respectively. With glutamate gamma-(3-carboxy-4-nitroanilide) as the donor, these Michaelis constants are 1.63, 16.6, and 12.3 mM. Glyclyglycine competitive inhibition constants with the parent donor and its carboxy derivative are 275 and 205 mM respectively; the non-competitive inhibition constant of the carboxy donor is 34 mM.

Polyphosphate Treatment of Frozen Cod. I. Protein Extractability and Lipid Hydrolysis

1964 ◽  
Vol 21 (1) ◽  
pp. 101-106 ◽  
Author(s):  
W. J. Dyer ◽  
H. Brockerhoff ◽  
R. J. Hoyle ◽  
D. I. Fraser
Keyword(s):  
Specific Effect ◽  
Lipid Hydrolysis ◽  
Ionic Concentrations ◽  
Extractable Protein ◽  
Protein Extractability

Tripolyphosphate dipped and undipped control paired cod fillets stored at −12 °C showed no differences occurring on storage in extractable protein, lipid hydrolysis, or thaw drip. A higher yield of frozen and of thawed fillets was obtained from the dipped samples due to water uptake.No specific effect of tripolyphosphate on thaw drip was obtained at the ionic concentrations used, but it is postulated that such effects might occur in the presence of about 1% salt.

Elimination of paraprotein interference in determination of plasma inorganic phosphate by ammonium molybdate method

1995 ◽  
Vol 41 (4) ◽  
pp. 609-614 ◽  
Author(s):  
Z Zaman ◽  
L Sneyers ◽  
A Van Orshoven ◽  
N Blanckaert ◽  
G Mariën
Keyword(s):  
Inorganic Phosphate ◽  
Ionic Concentration ◽  
Ammonium Molybdate ◽  
Phosphate Concentration ◽  
Light Chains ◽  
Plasma Phosphate ◽  
Free Light Chains ◽  
New Formulation ◽  
Molybdate Method

Abstract Phosphate concentrations were determined in 52 cases of paraproteinemia. The unmodified acidic ammonium molybdate method produced 19% spuriously high results. The false increase of phosphate concentration was attributable to formation of precipitate in the reaction mixture. The precipitate was formed by interaction between immunoglobulins and the unmodified acidic ammonium molybdate reagent. The magnitude of interference bore no relation to the type, concentrations, or isoelectric point of the paraproteins or to the presence or absence of free light chains. Diluting the sample to approximately 40 g/L total protein reduced but did not always eliminate the interference. In some cases paraprotein concentration as low as 8 g/L falsely increased plasma phosphate results. Apparently, only IgG and IgM but not IgA paraproteins produced the interference. Deproteination by ultrafiltration or by treatment with trichloroacetic acid removed the interference. The Kodak slide method and the new modified Boehringer Mannheim phosphate test were found to be interference-free. However, in some cases the latter new formulation is sensitive to substantial changes in ionic concentration of the reaction mixture.

Purification and properties of the cytosolic and mitochondrial forms of aspartate aminotransferase and malate dehydrogenase from rat heart

1987 ◽  
Vol 65 (3) ◽  
pp. 239-244 ◽  
Author(s):  
Charalampos Mavrides ◽  
Guylaine Nadeau
Keyword(s):  
Malate Dehydrogenase ◽  
Crude Extract ◽  
Aspartate Aminotransferase ◽  
Rat Heart ◽  
Pyridoxal Phosphate ◽  
Single Procedure ◽  
Purification And Properties ◽  
Michaelis Constants ◽  
Malate Aspartate Shuttle ◽  
Original Crude

The present work describes the purification from rat heart of the mitochondrial and cytosolic forms of the enzymes of the malate–aspartate shuttle, aspartate aminotransferase (EC 2.6.1.1) and malate dehydrogenase (EC 1.1.1.37), by a single procedure after the preparation of the original crude extract. In 10 purification steps, the four enzymes were obtained electrophoretically pure in yields ranging from 6 to 54% of their respective isoenzyme levels in the crude extract. Apoenzymes were formed from the aminotransferases by reacting them with cysteine sulfinate and dialyzing. Complete reconstitution was obtained after a brief incubation with pyridoxal phosphate. All four enzymes are dimers. The mitochondrial isoenzymes are of slightly lower molecular weight than their respective cytosolic forms. Michaelis constants and maximal velocities were derived by the use of primary and secondary plots. In general, the properties of the enzymes from rat heart are similar to the properties of the enzymes from other animal sources.

The Effect of Vitamin A on the Intermittent Nitrogen Dioxide Gas Exposure in Hamsters

1976 ◽  
Vol 34 ◽  
pp. 176-177
Author(s):  
J.C.S. Kim ◽  
M.G. Jourden ◽  
E.S. Carlisle
Keyword(s):  
Electron Microscopy ◽  
Vitamin A ◽  
Nitrogen Dioxide ◽  
Chronic Exposure ◽  
Light And Electron Microscopy ◽  
Specific Effect ◽  
Deficient Diet ◽  
Intermittent Exposure ◽  
Hypovitaminosis A ◽  
Gas Exposure

Chronic exposure to nitrogen dioxide in rodents has shown that injury reaches a maximum after 24 hours, and a reparative adaptive phase follows (1). Damage occurring in the terminal bronchioles and proximal portions of the alveolar ducts in rats has been extensively studied by both light and electron microscopy (1).The present study was undertaken to compare the response of lung tissue to intermittent exposure to 10 ppm of nitrogen dioxide gas for 4 hours per week, while the hamsters were on a vitamin A deficient diet. Ultrastructural observations made from lung tissues obtained from non-gas exposed, hypovitaminosis A animals and gas exposed animals fed a regular commercially prepared diet have been compared to elucidate the specific effect of vitamin A on nitrogen dioxide gas exposure. The interaction occurring between vitamin A and nitrogen dioxide gas has not previously been investigated.

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