scholarly journals Plasma clearance and endocytosis of mitochondrial malate dehydrogenase in the rat

1981 ◽  
Vol 200 (1) ◽  
pp. 115-121 ◽  
Author(s):  
M K Bijsterbosch ◽  
A M Duursma ◽  
J M W Bouma ◽  
M Gruber ◽  
P Nieuwenhuis
Keyword(s):  
Bone Marrow ◽  
Enzyme Activity ◽  
Malate Dehydrogenase ◽  
Plasma Clearance ◽  
Reticuloendothelial System ◽  
First Order ◽  
First Order Kinetics ◽  
Long Run ◽  
Mitochondrial Malate Dehydrogenase ◽  
Adsorptive Endocytosis

1. Pig mitochondrial malate dehydrogenase was labelled with 125I and intravenously injected into rats. Enzyme activity and radioactivity were cleared from plasma identically, with first-order kinetics, with a half-life of only 7 min. 2. Radioactivity accumulated in liver, spleen, bone (marrow) and kidneys, reaching maxima of 3 1, 4, 6 and 9% of the injected dose respectively, at 10 min after injection. 3. Our data allow us to calculate that in the long run 59, 5, 11 and 13% of the injected dose is taken up and subsequently broken down by liver, spleen, bone and kidneys respectively. 4. Differential fractionation of liver showed that the acid-precipitable radioactivity was mainly present in the lysosomal and microsomal fractions, suggesting that the endocytosed protein is transported via endosomes to lysosomes, where it is degraded. 5. Radioautography of liver and spleen suggested that the labelled protein was taken up by macrophages of the reticuloendothelial system. 6. Mitochondrial malate dehydrogenase is probably internalized in liver, spleen and bone marrow by adsorptive endocytosis, since uptake of the enzyme of these tissues is saturable.

scholarly journals Effect of liposomal phospholipid composition on cholesterol transfer between microsomal and liposomal vesicles

1986 ◽  
Vol 238 (3) ◽  
pp. 647-652 ◽  
Author(s):  
C Bhuvaneswaran ◽  
K A Mitropoulos
Keyword(s):  
Activation Energy ◽  
Enzyme Activity ◽  
Control System ◽  
Phospholipid Composition ◽  
Acyltransferase Activity ◽  
Phosphatidylcholine Liposomes ◽  
First Order ◽  
First Order Kinetics ◽  
Phospholipid Liposomes

Preincubation of rat liver microsomal vesicles at 37 degrees C in the presence of [3H]cholesterol/phospholipid liposomes results in a net transfer of cholesterol from liposomes to microsomal vesicles. This transfer follows first-order kinetics. For similar concentrations of the donor vesicles, rates of transfer are about 6-8 times lower with cholesterol/sphingomyelin liposomes compared with cholesterol/phosphatidylcholine liposomes. Also, transfer of cholesterol from cholesterol/sphingomyelin liposomes to microsomal vesicles reveals a larger activation energy than for the process from cholesterol/phosphatidylcholine liposomes. There is a significant correlation between the amount of liposomal cholesterol transferred to microsomal vesicles during preincubation and the increase found with acyl-CoA:cholesterol acyltransferase activity in these microsomes over their corresponding controls. If, however, liposomes made solely of phospholipids are substituted for the cholesterol/phospholipid liposomes in the preincubation system containing microsomal vesicles, then the acyl-CoA:cholesterol acyltransferase activity is decreased compared with the corresponding control system. Both sphingomyelin and phosphatidylcholine liposomes are equally effective in decreasing the enzyme activity. These results offer direct kinetic evidence for the positive correlation between cholesterol and sphingomyelin found in vivo in biological membranes.

scholarly journals Uptake of malate dehydrogenase into mitochondria in vitro. Some characteristics of the process

1983 ◽  
Vol 210 (1) ◽  
pp. 207-214 ◽  
Author(s):  
S Passarella ◽  
E Marra ◽  
S Doonan ◽  
E Quagliariello
Keyword(s):  
Enzyme Activity ◽  
Malate Dehydrogenase ◽  
The Other ◽  
Enzyme Treatment ◽  
Carbonyl Cyanide ◽  
Ion Gradient ◽  
Signal Probe ◽  
Energy Dependent ◽  
Mitochondrial Malate Dehydrogenase

1. It was previously shown [Passarella, Marra, Doonan & Quagliariello (1980) Biochem. J. 192, 649-658] that, when mitochondrial malate dehydrogenase from rat liver is incubated with sulphite-loaded mitochondria from the same source, uptake of the enzyme occurs, as judged by a fluorimetric assay of intramitochondrial enzyme activity. Confirmation of sequestration of the enzyme inside the organelles is provided by its proteinase-resistance after uptake. 2. Enzyme uptake into mitochondria is inhibited by enzyme treatment with mersalyl at concentrations that do not affect its catalytic activity. 3. Enzyme uptake is energy-dependent, as shown by inhibition of the process by carbonyl cyanide p-trifluoromethoxyphenylhydrazone and by antimycin. ATP and oligomycin, on the other hand, both stimulate the process, but stimulation by ATP is inhibited by oligomycin. These results suggest that uptake depends on maintenance of transmembrane ion gradient rather than direct ATP involvement. 4. Measurements of delta psi by means of the ‘redistribution signal’ probe safranine suggest no dependence of malate dehydrogenase uptake on membrane potential. 5. Comparison of the effects of the ionophores valinomycin, nonactin, gramicidin and nigericin shows that uptake depends on maintenance of a transmembrane pH gradient.

scholarly journals Mechanisms of thermoinactivation of endoglucanase I from Trichoderma reesei QM 9414

1992 ◽  
Vol 287 (2) ◽  
pp. 583-588 ◽  
Author(s):  
J M Dominguez ◽  
C Acebal ◽  
J Jimenez ◽  
I de la Mata ◽  
R Macarron ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Trichoderma Reesei ◽  
Time Course ◽  
Enzyme Concentration ◽  
Main Process ◽  
Peptide Bonds ◽  
First Order ◽  
First Order Kinetics ◽  
Endoglucanase I ◽  
Hydrolysis Of

The mechanism of irreversible thermoinactivation of endoglucanase I from Trichoderma reesei has been determined at 70 degrees C at the pH of maximum enzyme activity. The time-course of thermoinactivation did not follow first-order kinetics and kinetic constants of the process were dependent on enzyme concentration, suggesting that aggregation was the main process leading to irreversible inactivation. The enzyme was extremely resistant to urea, which in fact seemed to stabilize it against temperature. Disulphide exchange, deamidation and hydrolysis of peptide bonds were also responsible for the loss of enzyme activity at 70 degrees C.

Catabolism of circulating enzymes: plasma clearance, endocytosis, and breakdown of lactate dehydrogenase-1 in rabbits.

1988 ◽  
Vol 34 (12) ◽  
pp. 2475-2480 ◽  
Author(s):  
M J Smit ◽  
H Beekhuis ◽  
A M Duursma ◽  
J M Bouma ◽  
M Gruber
Keyword(s):  
Lactate Dehydrogenase ◽  
Trichloroacetic Acid ◽  
Plasma Clearance ◽  
Bladder Tissue ◽  
First Order ◽  
Tissue Sections ◽  
First Order Kinetics ◽  
Rapid Accumulation ◽  
Sinusoidal Liver Cells ◽  
Tissue Fractionation

Abstract Lactate dehydrogenase-1 (EC 1.1.1.27), intravenously injected into rabbits, was cleared with first-order kinetics (half-life 27 min), until at least 80% of the injected activity had disappeared from plasma. Radioactivity from injected 125I-labeled enzyme disappeared at this same rate. Trichloroacetic-acid-soluble breakdown products started to appear in the circulation shortly after injection of the labeled enzyme. Body scans of the rabbits for 80 min after injection of 131I-labeled enzyme revealed rapid accumulation of label in the liver, peaking 10-20 min after injection. Subsequently, activity in the liver declined and radioactivity (probably labeled breakdown products of low molecular mass) steadily accumulated in the bladder. Tissue fractionation of liver, 19 min after injection of labeled enzyme, indicated that the radioactivity was present both in endosomes and in lysosomes, suggesting uptake by endocytosis, followed by breakdown in the lysosomes. Measurements of radioactivity in liver and plasma suggest that the liver is responsible for the breakdown of at least 75% of the injected enzyme. Radioautography of tissue sections of liver and spleen showed accumulated radioactivity in sinusoidal liver cells and red pulpa, respectively. These results are very similar to those for lactate dehydrogenase-5, creatine kinase MM, and several other enzymes that we have previously studied in rats.

scholarly journals STUDIES ON THE CONFORMATIONAL CHANGES OF MITOCHONDRIAL MALATE DEHYDROGENASE IN UREA–PHOSPHATE SOLUTIONS

1967 ◽  
Vol 45 (5) ◽  
pp. 659-669 ◽  
Author(s):  
R. J. Seguin ◽  
G. W. Kosicki
Keyword(s):  
Malate Dehydrogenase ◽  
Conformational Changes ◽  
Inorganic Phosphate ◽  
Protein Molecule ◽  
Order Rate Constant ◽  
Sulfhydryl Groups ◽  
First Order ◽  
Phosphate Ions ◽  
Mitochondrial Malate Dehydrogenase ◽  
Phosphate Solutions

Pig-heart mitochondrial malate dehydrogenase is gradually inactivated in 4 M urea. During the inactivation, sulfhydryl groups on the protein are exposed in a first-order reaction. The reaction is followed spectrophotometricaily using the sulfhydryl reagent, 5,5′-dithiobis(2-nitrobenzoate) (DTNB). Titration with DTNB in the presence of urea exposes 10 to 12 sulfhydryl groups per molecule of mitochondrial malate dehydrogenase. The enzyme is also inactivated when diluted in water but no sulfhydryl groups are unmasked. The loss of activity and the appearance of sulfhydryl groups in urea solutions do not take place at the same rate.The conformational changes of malate dehydrogenase that occur in urea solutions are partially prevented by inorganic phosphate ions, and less so by the substrates NADH, NAD+, oxalacetate (OAA), and L-malate. The protection against loss of enzyme activity by inorganic phosphate ions is pH-dependent. Both inorganic phosphate and NADH considerably reduce the first-order rate constant for sulfhydryl appearance in 4 M urea. Protection of the enzyme against sulfhydryl appearance in urea solutions by pre-incubation with the substrates indicates that about two sulfhydryl groups per molecule of mitochondrial malate dehydrogenase are involved in substrate binding. Thus, the substrates must keep the active site of the enzyme intact. They either bind to the sulfhydryl groups or prevent the protein molecule from completely unfolding.

scholarly journals Plasma clearance and endocytosis of cytosolic malate dehydrogenase in the rat

1983 ◽  
Vol 210 (2) ◽  
pp. 419-428 ◽  
Author(s):  
M K Bijsterbosch ◽  
A M Duursma ◽  
J M W Bouma ◽  
M Gruber
Keyword(s):  
Bone Marrow ◽  
Malate Dehydrogenase ◽  
Half Life ◽  
Cell Protein ◽  
Net Charge ◽  
Lysosomal Fraction ◽  
First Order Kinetics ◽  
Parenchymal Cells ◽  
Cytosolic Malate Dehydrogenase ◽  
Positively Charged

1. Pig heart cytosolic malate dehydrogenase was radiolabelled with O-(4-diazo-3,5-di-[125I]iodobenzoyl)sucrose and intravenously injected into rats. Enzyme activity and radioactivity were cleared from plasma identically, with first-order kinetics, with a half-life of about 30 min. 2. The tissue distribution of radioactivity was determined at 2 h after injection. All injected radioactivity was recovered from the tissues. A high percentage of the injected dose was found in liver (37%), spleen (6%) and bone including marrow (19%). 3. Radioactivity in liver and spleen increased up to 2 h after injection and subsequently declined, with a half-life of about 20 h. 4. After differential fractionation of liver, radioactivity was largely found in the mitochondrial and lysosomal fraction. 5. Liver cells were isolated 1 h after injection of labelled enzyme. We found that Kupffer cells, endothelial cells and parenchymal cells had endocytosed the enzyme at rates corresponding to 2725, 94 and 63 ml of plasma/day per g of cell protein respectively. 6. Radioautography indicated that in spleen and bone marrow the enzyme is mainly taken up by macrophages. 7. Internalization of the enzyme by liver, spleen and bone marrow was saturable. This indicates that the enzyme is taken up in these tissues by adsorptive endocytosis. 8. The present results closely resemble those obtained previously for the mitochondrial isoenzyme of malate dehydrogenase and for lactate dehydrogenase M4. Since those enzymes are positively charged at physiological pH, whereas cytosolic malate dehydrogenase is negative, net charge cannot be the major factor determining the rate of uptake of circulating enzymes by reticuloendothelial macrophages, as has been suggested in the literature [Wachsmuth & Klingmüller (1978) J. Reticuloendothel. Soc. 24, 227-241].

scholarly journals Endocytosis and breakdown of mitochondrial malate dehydrogenase in the rat in vivo. Effects of suramin and leupeptin

1982 ◽  
Vol 208 (1) ◽  
pp. 61-67 ◽  
Author(s):  
M K Bijsterbosch ◽  
A M Duursma ◽  
J M W Bouma ◽  
M Gruber
Keyword(s):  
Bone Marrow ◽  
Malate Dehydrogenase ◽  
Kupffer Cells ◽  
Cell Types ◽  
Cell Protein ◽  
Carbon Particles ◽  
Parenchymal Cells ◽  
In Vivo Effects ◽  
Mitochondrial Malate Dehydrogenase

1. The plasma clearance of intravenously injected 125I-labelled mitochondrial malate dehydrogenase (half-life 7 min) was not influenced by previous injection of suramin and/or leupeptin (inhibitors of intralysosomal proteolysis). 2. Pretreatment with both inhibitors considerably delayed degradation of endocytosed enzyme in liver, spleen, bone marrow and kidneys. 3. The tissue distribution of radioactivity was determined at 30 min after injection, when only 3% of the dose was left in plasma. All injected radioactivity was still present in the carcass. The major part of the injected dose was found in liver (49%), spleen (5%), kidneys (13%) and bone, including marrow (11%). 4. Liver cells were isolated 15 min after injection of labelled enzyme. We found that Kupffer cells and parenchymal cells had endocytosed the enzyme at rates corresponding to 9530 and 156 ml of plasma/day per g of cell protein respectively. Endothelial cells do not significantly contribute to uptake of the enzyme. 5. Uptake by Kupffer cells was saturable, whereas uptake by parenchymal cells was not. This suggests that these cell types endocytose the enzyme via different receptors. 6. Previous injection of carbon particles greatly decreased uptake of the enzyme by liver, spleen and bone marrow.

Photo-catalytic degradation of gaseous pollutants in paper mills of southern China

TAPPI Journal ◽  
2018 ◽  
Vol 17 (03) ◽  
pp. 167-178 ◽  
Author(s):  
Xin Tong ◽  
Jiao Li ◽  
Jun Ma ◽  
Xiaoquan Chen ◽  
Wenhao Shen
Keyword(s):  
Degradation Rate ◽  
Southern China ◽  
Catalytic Degradation ◽  
Pulp And Paper ◽  
Gaseous Pollutants ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Initial Concentration ◽  
First Order ◽  
First Order Kinetics

Studies were undertaken to evaluate gaseous pollutants in workplace air within pulp and paper mills and to consider the effectiveness of photo-catalytic treatment of this air. Ambient air at 30 sampling sites in five pulp and paper mills of southern China were sampled and analyzed. The results revealed that formaldehyde and various benzene-based molecules were the main gaseous pollutants at these five mills. A photo-catalytic reactor system with titanium dioxide (TiO2) was developed and evaluated for degradation of formaldehyde, benzene and their mixtures. The experimental results demonstrated that both formaldehyde and benzene in their pure forms could be completely photo-catalytic degraded, though the degradation of benzene was much more difficult than that for formaldehyde. Study of the photo-catalytic degradation kinetics revealed that the degradation rate of formaldehyde increased with initial concentration fitting a first-order kinetics reaction. In contrast, the degradation rate of benzene had no relationship with initial concentration and degradation did not conform to first-order kinetics. The photo-catalytic degradation of formaldehyde-benzene mixtures indicated that formaldehyde behaved differently than when treated in its pure form. The degradation time was two times longer and the kinetics did not reflect a first-order reaction. The degradation of benzene was similar in both pure form and when mixed with formaldehyde.

EMPIRICAL ANALYSIS OF INDIA’S FOREIGN TRADE AND ECONOMIC GROWTH

2020 ◽  
Vol 8 (10) ◽  
pp. 105-111
Author(s):  
Khujan Singh ◽  
Anil Kumar
Keyword(s):  
Time Series Data ◽  
Unit Root Test ◽  
Series Data ◽  
Significant Implication ◽  
Causality Test ◽  
First Order ◽  
Long Run ◽  
Directional Relation ◽  
Augmented Dickey Fuller ◽  
Vecm Granger Causality

The present study is an attempt to examine long run relationship among India’s GDP, Exports and Imports for which yearly time series data from 1995 to 2018 has been collected. Data for India’s GDP has been collected from RBI website and India’s export and import data has been collected form Ministry of Commerce and Industry website. The Augmented Dickey-Fuller unit root test for stationarity found that studied variables become stationary at first order of difference. While, Johnson cointegration test revealed long run cointegration between India’s GDP, exports and imports. The results of VECM Granger causality test exhibited bi-directional relationship between India’s GDP and India’s exports, whereas uni-directional relation has been found between India’s GDP and India’s imports. These results have significant implication for India’s export import policy and to achieve a target of $5 trillion economy till 2024-2025.

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