Mitochondrial malate dehydrogenase of watermelon cotyledons: Time course and mode of enzyme activity changes during germination

Planta ◽  
1976 ◽  
Vol 129 (1) ◽  
pp. 27-32 ◽  
Author(s):  
R.-A. Walk ◽  
B. Hock
Keyword(s):  
Enzyme Activity ◽  
Malate Dehydrogenase ◽  
Time Course ◽  
Mitochondrial Malate Dehydrogenase

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 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 Ontogeny of malate-aspartate shuttle capacity and gene expression in cardiac mitochondria

1998 ◽  
Vol 274 (3) ◽  
pp. C780-C788 ◽  
Author(s):  
Thomas D. Scholz ◽  
Stacia L. Koppenhafer ◽  
Cynthia J. Teneyck ◽  
Brian C. Schutte
Keyword(s):  
Gene Expression ◽  
Malate Dehydrogenase ◽  
Posttranscriptional Regulation ◽  
Time Course ◽  
Cardiac Tissue ◽  
Mrna Levels ◽  
Cardiac Mitochondria ◽  
Protein Levels ◽  
Mitochondrial Malate Dehydrogenase ◽  
Malate Aspartate Shuttle

Developmental downregulation of the malate-aspartate shuttle has been observed in cardiac mitochondria. The goals of this study were to determine the time course of the postnatal decline and to identify potential regulatory sites by measuring steady-state myocardial mRNA and protein levels of the mitochondrial proteins involved in the shuttle. By use of isolated porcine cardiac mitochondria incubated with saturating concentrations of the cytosolic components of the malate-aspartate shuttle, shuttle capacity was found to decline by ∼50% during the first 5 wk of life (from 921 ± 48 to 531 ± 53 nmol ⋅ min−1 ⋅ mg protein−1). Mitochondrial aspartate aminotransferase mRNA levels were greater in adult than in newborn myocardium. mRNA levels of mitochondrial malate dehydrogenase in adult cardiac tissue were 224% of levels in newborn tissue, whereas protein levels were 54% greater in adult myocardium. Aspartate/glutamate carrier protein levels were also greater in adult than in newborn tissue. mRNA and protein levels of the oxoglutarate/malate carrier were increased in newborn myocardium. It was concluded that 1) myocardial malate-aspartate shuttle capacity declines rapidly after birth, 2) divergence of mitochondrial malate dehydrogenase mRNA and protein levels during development suggests posttranscriptional regulation of this protein, and 3) the developmental decline in malate-aspartate shuttle capacity is regulated by decreased oxoglutarate/malate carrier gene expression.

Comparison of the precursor and mature forms of rat heart mitochondrial malate dehydrogenase

Biochemistry ◽  
1987 ◽  
Vol 26 (1) ◽  
pp. 128-134 ◽  
Author(s):  
Paula M. Grant ◽  
Steven L. Roderick ◽  
Gregory A. Grant ◽  
Leonard J. Banaszak ◽  
Arnold W. Strauss
Keyword(s):  
Malate Dehydrogenase ◽  
Rat Heart ◽  
Mitochondrial Malate Dehydrogenase

scholarly journals Rat uterine microbiochemistry: metabolic enzyme activities stimulated by 17-beta-estradiol are localized in epithelial cells.

1987 ◽  
Vol 35 (6) ◽  
pp. 657-662 ◽  
Author(s):  
J P Holt ◽  
E Rhe
Keyword(s):  
Enzyme Activity ◽  
Smooth Muscle ◽  
Epithelial Cells ◽  
Dose Response ◽  
Enzyme Activities ◽  
Time Course ◽  
Citrate Synthase ◽  
Ovariectomized Rats ◽  
Similar Response ◽  
Estradiol Treatment

Lactate dehydrogenase (LDH; EC 1.1.1.27), citrate synthase (CS; EC 4.1.3.7), and beta-hydroxyacyl-CoA-dehydrogenase (beta-OH-acyl-CoA-DH; EC 1.1.1.35) activities were determined in each of the three major cell types of rat uterus, i.e., epithelial, stromal, and smooth muscle, using quantitative microanalytical techniques. Adult ovariectomized rats were treated with 17-beta-estradiol to determine the time course and dose response (0.025-50 micrograms/300-g rat) effect of estrogen on enzyme activity of each type of uterine cell. The use of "oil well" and enzyme-cycling microtechniques to determine the time course and the dose responses of enzyme activity changes required microassays involving 1595 microdissected single cell specimens. Estradiol treatment increased epithelial LDH, CS and beta-OH-acyl-CoA-DH activity but had no effect on these enzymes in the stroma or in smooth muscle cells. The estradiol-stimulated peak enzyme activities on Day 4 in the intervention group are compared with those in the ovariectomized rat controls as follows: LDH, 44.5 +/- 3.5 vs 22.3 +/- 3.9; CS, 3.5 +/- 0.2 vs 1.5 +/- 0.6; beta-OH-acyl-CoA-H, 3.5 +/- 0.32 vs 2.2 +/- 0.2 (mean +/- standard deviation; mol/kg/hr). Stromal cell activities (LDH, 7.4 +/- 1.0; CS, 1.2 +/- 0.2; beta-OH-acyl-CoA-DH, 0.9 +/- 0.1) were significantly lower than epithelial cell levels and were similar to smooth muscle levels. Therefore, even in the ovariectomized animal epithelial cells have markedly higher metabolic activity compared with adjacent cells. The enzyme activities are expressed as moles of substrate reacting per kilogram of dry weight per hour. All three enzymes exhibited a 17-beta-estradiol-induced dose response between 0.025-0.15 micrograms/300-g rat. The three enzymes studied all had similar response patterns to estrogen. The effect of estradiol was restricted to epithelial cells, with enzyme activities increasing to maximal levels after approximately 96 hr of hormone treatment. This study therefore not only confirms the specific and differential metabolic responses of uterine cells to estradiol treatment, but clearly demonstrates that marked metabolic differences exist between epithelial cells and stromal or smooth muscle uterine cells.

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