Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.3.5.1 (succinate dehydrogenase)
8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The oxidation of formaldehyde by rat liver mitochondria in the presence of 50 mM phosphate was enhanced 2-fold by exogenous NAD+. Absolute requirement of NAD+ for formaldehyde oxidation was demonstrated by depleting the mitochondria of their NAD+ content (4.6 nmol/mg of protein), followed by reincorporation of the NAD+ into the depleted mitochondria. Aldehyde (formaldehyde) dehydrogenase activity was completely abolished in the depleted mitochondria, but the enzyme activity was restored to control levels following reincorporation of the pyridine nucleotide. Phosphate stimulation of formaldehyde oxidation could not be explained fully by the phosphate-induced swelling which enhances membrane permeability to NAD+, since stimulation of the enzyme activity by increased phosphate concentrations was still observed in the absence of exogenous NAD+. The Km for formaldehyde oxidation by the mitochondria was found to be 0.38 nM, a value similar to that obtained with varying concentrations of NAD+; both Vmax values were very similar, giving a value of 70 to 80 nmol/min/mg of protein. The pH optimum for the mitochondrial enzyme was 8.0. Inhibition of the enzyme activity by anaerobiosis was apparently due to the inability of the respiratory chain to oxidize the generated NADH. The inhibition of mitochondrial formaldehyde oxidation by succinate was found to be due to a lowering of the NAD+ level in the mitochondria. Succinate also inhibited acetaldehyde oxidation by the mitochondria. Malonate, a competitive inhibitor of succinic dehydrogenase, blocked the inhibitory effect of succinate. The respiratory chain inhibitors, rotenone, and antimycin A plus succinate, strongly inhibited formaldehyde oxidation by apparently the same mechanism, although the crude enzyme preparation (freed from the membrane) was slightly sensitive to rotenone. The mitochondria were subfractionated, and 85% of the enzyme activity was found in the inner membrane fraction (mitoplast). Furthermore, separation into inner membrane and matrix components indicated a distribution of aldehyde dehydrogenase activity similar to malic dehydrogenase.
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PMID:Biochemical properties of rat liver mitochondrial aldehyde dehydrogenase with respect to oxidation of formaldehyde. 17 56

Leupeptin (acyl peptidyl-L-argininal) is a potent inhibitor of trypsin and related proteases. We analyzed the association of leupeptim with bovine trypsin kinetically, assuming that it proceeds by a pathway which involves two steps: E + I in equilibrium K1 Complex I k-2 in equilibrium k+2 Complex II. The observed dissociation constant (K1) for the first step was 1.24 X 10(-3) M (at pH 8.2 15 degrees C) and the two first-order rate constants (k+2 and k-2) were 166 s-1 and 1.75 X 10(-3.s-1, respectively (at pH 8.2, 15 degrees C). The dissociation constant (Kd) for the whole process was calculated from these parameters to be 1.34 X 10(-8) M. This value is compatible with that determined directly by an independent static method (2.36 X 10(-8) M). We also measured Kd for the leupeptine complex of anhydrotrypsin, a trypsin derivative in which the active-site hydroxyl group is missing. The observed value was about 5 orders of magnitude larger than Kd and was rather similar to K1 in native trypsin. A elupeptin isomer which contains a D-argininal residue did not show strong affinity towards trypsin. These findings suggest that complex II consists of a covalent hemiacetal adduct formed between the serine hydroxyl group in the enzyme active site and the aldehyde group in the inhibitor. The pH dependencies of the dissociation constant and other parameters show that deprotonation of the charge-relay sustem in the active site is important for the formation and stabilization of complex II.
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PMID:Mechanism of association of a specific aldehyde inhibitor, leupeptin, with bovine trypsin. 57 67

The paper deals with studying the effect of vitamin A deficit in the rat organism on the incorporation of the C14-labelled asparaginic acid serine-3-C14 and glycine-2-C14 into different fractions of skin proteins, with determining the content of glycine cycle components (glycine, glycolic acid and glycolic aldehyde), activity of phosphatases and succinate dehydrogenase in the skin as well as the quantity of mucopolysaccharides and seromucoids in the skin and blood serum. It is established that with vitamin A deficit the intensity of the incorporation of labelled asparaginic acid and serine into the skin total proteins decreases and the incorporation of glycine-2-C14 into the total proteins and the fraction of soluble non-collagen proteins of skin increases. The intensity of the incorporation of the labelled asparaginic acid into the skin soluble collagen falls by 40% but almost twice as high into the soluble non-collagen proteins. A 47% decrease of glycine, 22% fall of glycolic acid and almost two-fold increase of glycolic aldehyde are observed in the skin of the animals with A-avitaminosis. Skin extracts manifest a higher activity of alkaline and acid phosphatases, but a lower activity of succinate dehydrogenase in comparison with control.
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PMID:[Some peculiarities of skin metabolism with vitamin A deficit]. 120 63

Incubation of aldehyde dehydrogenase-free mitochondrial preparations with biogenic amines serotonin, tyramine, 2-phenylethylamine and 5-methoxytryptamine resulted in inhibition of enzymes activity of both outer (rotenone-insensitive NADH-cytochrome c reductase) and inner (succinate dehydrogenase, succinate cytochrome c reductase) mitochondrial membranes. Solubilization of mitochondria after the incubation did not influence the amine-induced alteration of succinate dehydrogenase activity. Pretreatment of the organelles with a mixture containing chlorgyline and deprenyl completely inhibited monoamine oxidase (MAO) activity and prevented the effects of all the amines studied on mitochondrial enzymes. MAO-dependent effects of 5-methoxytryptamine were fully reproduced by 5-methoxyindolyl-3-acetaldehyde (one of probable products of 5-methoxytryptamine deamination). The effect of the aldehyde was not prevented by chlorgyline and deprenyl. After selective inhibition of MAO-A by chlorgyline the order of MAO-B-dependent effects of biogenic amines on mitochondrial enzymes studied was as follows: tyramine greater than or equal to 2-phenylethylamine much greater than serotonin. In deprenyl pretreated mitochondria the potency of MAO-A-dependent effects of these amines was: serotonin greater than tyramine much greater than much greater than 2-phenylethylamine. The data obtained suggest that the product(s) of oxidative deamination of biogenic amines (probably the aldehydes) catalyzed by both types of MAO (MAO-A and MAO-B) are able to regulate the energy functions of mitochondria.
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PMID:[The role of monoamine oxidase in the regulation of mitochondrial energy functions]. 175 90

In the liver mitochondrial fraction of the first generation offspring of alcoholized male rats, decreased activities of monoamine oxidase (MAO) types A and B, rotenone-insensitive NADH-cytochrome c-reductase and succinate dehydrogenase were observed. The MAO-dependent inhibition of rotenone-insensitive NADH-cytochrome c-reductase and succinate dehydrogenase by biogenic amines, incubated with the mitochondrial fraction, was altered in the offspring of alcoholized animals as compared with control rats. The sensitivity of these enzymatic activities towards the inhibitory effect of 5-methoxyindol-3-ylacetaldehyde was markedly increased in the offspring of alcoholized male rats. The data obtained suggest the existence of a genetically determined predisposition of the mitochondrial metabolic processes in the offspring of the alcoholized rats to the effects of ethanol and to the toxic effects of acetaldehyde, formed during ethanol metabolism.
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PMID:Studies on mitochondrial metabolic processes in offspring of alcoholized rats--I. Evidence for altered activity and sensitivity to monoamine oxidase-dependent control by biogenic amines of some membrane-bound enzymes. 180 36

Young adult Wistar rats received 40 mg/kg of cyclosporin perorally for 21 days. Cyclosporin induced almost total disappearance of thymic medulla, whereas the cortex remained preserved. Although the density of cortical macrophages did not change significantly, their characteristics altered markedly and they became enlarged and rounded. In addition to an increase in acid phosphatase and nonspecific esterase activities, cortical macrophages developed very strong succinic dehydrogenase and chloroacetate esterase activities and a fine, granular, aldehyde fuchsin-positive cytoplasmic content. However, these cytoplasmic granules were PAS-negative and were not sudanophilic. Cortical macrophages retained their normal antigenic properties (which were studied by the use of ED1, ED2 and R-MC 41 monoclonal antibodies). Phagocytic cells in the remaining medullary islands retained their usual characteristics. The changes in cortical macrophages after cyclosporin treatment are discussed, especially in relation to the characteristics of macrophages of the cortico-medullary zone in the normal rat thymus.
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PMID:Macrophages of the rat thymus after cyclosporin treatment. Histochemical, enzymehistochemical and immunohistochemical study. 256 84

Secondary lymphoid follicles in peripheral lymphoid organs (parathymic, mesenteric and inguinal lymph nodes and spleen) from young adult Wistar rats of both sexes were studied. Different numbers of tingible body macrophages containing aldehyde fuchsin-positive cytoplasmic granules of varying size, were present in the germinal centers. An identical staining pattern to that obtained with aldehyde fuchsin in terms of the number, distribution and size of positive cells was seen after staining for succinic dehydrogenase.
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PMID:Succinic dehydrogenase activity in germinal center macrophages in peripheral lymphoid organs of the rat. 288 60

The myocardium and blood vessels of 20 rats kept for one year on DeCarli and Lieber's liquid diet containing alcohol to 36% of total Joules were examined with routine histological, histochemical and electron microscopical methods. No changes in the gross anatomy, histology, histochemistry and electron microscopy of the arteries, veins and capillaries were found. Subcellular damage of the atrial and ventricular myocardial cells was observed. A varying number of mitochondria were affected in each of the animals: degenerated mitochondria, mitochondria with electron lucent matrix, with concentric cristae, of bell shape, with negative succinic dehydrogenase activity or vacuolated mitochondria were found. In 10% the myofibrils, and in 30% the sarcoplasmic reticulum were damaged. Secretion and lipofuscin granules increased in number in 25% of the animals. It is concluded that although the submicroscopic alcoholic alterations are similar to some of those reported in experimental ischaemia, the decrease in myocardial blood flow may not be held solely responsible for the alcoholic damages. A toxic effect of alcohol, acetaldehyde and catecholamine is postulated.
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PMID:Morphological alterations due to long term alcohol intake in rats. 360 39

The cortex and medulla of the normal rat thymus are populated with scattered cells which are strongly positive for acid phosphatase and only weakly (cortex) or moderately (medulla) positive for nonspecific esterase. Corticomedullary zone is characterized, as a specific entity within the thymic tissue, by the presence of very large macrophages, highly positive for acid phosphatase and nonspecific esterase. Moreover, these cells, located exclusively in the corticomedullary zone, show very strong succinic dehydrogenase activity and contain the intracytoplasmic granules of varying size, which are aldehyde fuchsin, PAS, and oil red O positive. The presence of cholesterol was demonstrated within the lipid content.
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PMID:Enzyme-histochemical characterization of macrophages in the rat thymus, with special reference to metallophilic cells of the corticomedullary zone. 620 53

Baboons fed ethanol (50% of total calories) chronically develop ultrastructural alterations of hepatic mitochondria. To determine whether mitochondrial functions are also altered, mitochondria were isolated from nine baboons fed ethanol chronically and their pair-fed controls. At the fatty liver stage, ADP-stimulated respiration was depressed in ethanol-fed baboons by 59.4% with glutamate, 43.2% with acetaldehyde, 45.1% with succinate and 51.1% with ascorbate as substrates. A similar decrease was noted in the ADP/O ratio (14 to 28%) and respiratory control ratio (20 to 44%) with all substrates. Similar alterations of mitochondrial functions were observed in baboons with more advanced stages of liver disease, namely fibrosis. These changes after ethanol treatment were associated with decreases in the enzyme activities of mitochondrial respiratory chain: glutamate, NADH and succinate dehydrogenase (42, 24 and 28%, respectively), glutamate-, NADH- or succinate-cytochrome c reductase (42, 27 and 32%, respectively) and cytochrome oxidase (59.6%). The content of all cytochromes was also decreased in ethanol-fed baboons, especially aa3 (57%). Moreover, [14C]leucine incorporation into mitochondrial membranes was depressed by 21% after ethanol treatment. On the other hand, glutamate dehydrogenase activities of serum and cytosol in ethanol-fed baboons were significantly higher than those in pair-fed controls. Morphologically, mitochondria of ethanol-fed baboons were larger than those of pair-fed controls. However, the mitochondrial protein content per mitochondrial DNA was unchanged. From these results, we conclude that, morphologically and functionally, hepatic mitochondria in baboons are altered by chronic ethanol consumption; it is noteworthy that these changes are fully developed already at the fatty liver stage, and that morphological alteration appears to reflect the damage of mitochondrial membranes rather than an adaptive hypertrophy.
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PMID:Biochemical and morphological alterations of baboon hepatic mitochondria after chronic ethanol consumption. 653 46


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