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)

Soluble succinate dehydrogenase prepared by butanol extraction reacts with N-ethylmaleimide according to first-order kinetics with respect to both remaining active enzyme and the inhibitor concentration. Binding of the sulfhydryl groups of the enzyme prevents its alkylation by N-ethylmaleimide and inhibition by oxaloacetate. A kinetic analysis of the inactivation of alkylating reagent in the presence of succinate or malonate suggests that N-ethylmaleimide acts as a site-directed inhibitor. The apparent first-order rate constant of alkylation increases between pH 5.8 and 7.8 indicating a pKa value for the enzyme sulfhydryl group equal to 7.0 at 22 degrees C in 50 mM Tris-sufate buffer. Certain anions (phosphate, citrate, maleate and acetate) decrease the reactivity of the enzyme towards the alkylating reagent. Succinate/phenazine methosulfate reductase activity measured in the presence of a saturating concentration of succinate shows the same pH-dependence as the alkylation rate by N-ethylmaleimide. The mechanism of the first step of succinate oxidation, including a nucleophilic attack of substrate by the active-site sulfhydryl group, is discussed.
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PMID:Reactivity of the sulfhydryl groups of soluble succinate dehydrogenase. 0 20

This paper reports on the discovery of a protein kinase activity associated with the inner membrane of mammalian mitochondria. The enzyme does not respond to addition of cyclic AMP or cyclic GMP and has a preference for whole histone as phosphate acceptor. Some standard assay systems for the cyclic nucleotide-dependent cytosol protein kinases would be unable to pick up this activity of the orthophosphate concentration is higher than 25 mM and the pH or the assay lower than pH 6.5. The enzyme described here has an apparent pH optimum of 8.5. Activity in liver mitochondria is not evident unless the mitochondria are disrupted by either sonication or freezing and thawing. Distribution of kinase activity in centrifugal fractions of both liver and heart mitochondrial sonicates was parallel to that of the two inner membrane marker enzymes succinic dehydrogenase and cytochrome oxidase and quite different from that of the matrix enzyme malic dehydrogenase. Experiments with preparations enriched in outer or inner membranes confirmed the contention that this enzyme is located on the inner membrane. Since disruption of the inner membrane by a freeze-thaw treatment (after the outer membrane had been disrupted by swelling in phosphate) was necessary for full expression of activity by this enzyme, the tentative conclusion was reached that substrate is accepted only from the matrix side of the inner membrane.
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PMID:Protein kinase activity at the inner membrane of mammalian mitochondria. 1 32

Mammalian and avian muscles were examined histochemically and biochemically to determine the relative contribution of membrane bound (mitochondrial and sarcotubular) ATPases under the same conditions employed for myofibrillar ATPase. For histochemically investigated Ca+(+)-ATPase activity following incubation at pH 9.4 according to the calcium-citro-phosphate technique, avian muscle displayed distinct mitochondrial localization in both dark and light staining fibres. However, mitochondrial localization did not occur in mammalian muscle fibres. Pretreatment of unfixed frozen sections with ouabain, cyanide and acetone did not prevent the reticular distribution in avian muscle fibres. The present study demonstrates that "myofibrillar" localization is achieved by the Ca+(+)-precipitation technique: provided frozen sections are pretreated with cold acetone, fixed in a fixative containing oligomycin or azide and then incubated in a medium containing glycine-NaO H as buffer. Mitochondria prepared by successive mechanical homogenization or by Nagarse treatment plus 2 min homogenization develop different ATPase activities at pH 9.4 7.4 6.0 and 4.35 as well as stimulation by 70 mM Ca++ at these pHs compared to those ATPase activities in the homogenate of mixed hamster hind leg muscles. Glycerol-3-phosphate dehydrogenase and creatine kinase (both located at the outer surface of the inner mitochondrial membrane) and succinate dehydrogenase and glutamate dehydrogenase (localized at the inner mitochondrial membrane and in the matrix resp.) also show different activities in both mitochondria preparations indicating different membrane properties of both mitochondria. Evidence is obtained that using the calcium-citro-phosphate technique at pH 9.4 oligomycin-sensitive and -insensitive ATPases are activated by Ca++ in both mitochondria preparations. Since in muscle homogenate less than 10% of Ca+(+)-stimulated ATPase activity is oligomycin-sensitive, mitochondrial ATPase exhibit only a small portion of total ATPase from mixed hamster hind leg muscles.
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PMID:Histochemical and biochemical investigations of adenosine triphosphatase in vertebrate mixed muscles. 4 33

Exposure of male rats to parathion (2.6 mg/kg), lindane (17.6 mg/kg), or their combination through oral intubation daily for a period of 90 days produced histological and biochemical alterations in the liver and testis. The focal necrosis of the liver, although observed in all the treatments, was very prominent in the animals exposed to lindane alone. The kidney and epididymis, however, did not show any significant histological lesions. The activity of acetylcholine esterase in blood and brain decreased markedly, whereas that of succinic dehydrogenase, adenosine triphosphatase, and the alkaline and acid phosphate in liver and testis showed significant alterations for all three treatments.
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PMID:Comparative response of male rats to parathion and lindane: histopathological and biochemical studies. 9 96

When Cladosporium resinae is provided with n-hexadecane and glucose, n-hexadecane is used preferentially. Studies using [14C]glucose indicated that n-hexadecane did not inhibit glucose uptake but did retard oxidation of glucose to CO2 and assimilation of glucose carbon into trichloroacetic acid-insoluble material. Glucose could be recovered quantitatively from hydrocarbon-grown cells that had been transferred to glucose. Four enzymes that may be involved in glucose metabolism, hexokinase, glucose-6-phosphate dehydrogenase, glucose-phosphate isomerase, and succinate dehydrogenase, were not detected in cells grown on hexadecane but were present in cells grown on glucose. Addition of hexadecane to extracts of glucose-grown cells resulted in immediate loss of activity for each of the four enzymes, but two other enzymes did not directly involved in glucose metabolism, adenosine triphosphatase and alanine-ketoacid aminotransferase, were not inhibited by hexadecane in vitro. Cells grown on hexadecane and transferred to glucose metabolize intracellular hexadecane; after 1 day, activity of hexokinase, glucose-6-phosphate dehydrogenase, glucosephosphate isomerase, and succinate dehydrogenase could be detected and 22% of the intracellular hydrocarbon had been metabolized. Hexadecane-grown cells transferred to glucose plus cycloheximide showed the same level of activity of all the four enzymes as cells transferred to glucose alone. Thus, intracellular n-hexadecane or a metabolite of hexadecane can inthesis of those enzymes is not inhibited.
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PMID:Inhibition of glucose metabolism by n-hexadecane in Cladosporium (Amorphotheca) resinae. 13 54

Three glycerol-nonutilizing mutants deficient in the mitochondrial glycerol-3-phosphate (G3P) dehydrogenase (EC 1.1.99.5) were isolated from inl(ts) derivatives of Neurospora crassa following inositolless death at elevated temperatures on minimal glycerol medium. These mutants failed to grow on glycerol as a sole carbon source, but could grow on acetate, glucose, or mannitol media and were female fertile in genetic crosses, thereby distinguishing them from the previously reported polyol-protoperithecial defective Neurospora mutants. In addition, these glp mutants exhibited a distinct morphological alteration during vegetative growth on sucrose slants and colonial growth on sorbose-containing semicomplete medium. The glp-2 locus was assigned a location between arg-5 and nuc-2 on chromosome IIR on the basis of two-factor crosses and by duplication coverage by insertional translocation ALS176, but not NM177. All mutations were allelic as judged from the absence of both complementation in forced heterokaryons and genetic recombination among glp-2 mutations. The reversion frequency of all three mutations was less than 10(10), indicating probable deletions in these strains. No G3P dehydrogenase activity could be detected in either cytosolic or mitochondrial extracts from mutant strains grown on glycerol, glucose, or galactose media. These results suggest that the glp-2 locus may be the structural gene for both the cytosolic and mitochondrial forms of G3P dehydrogenase or for a cytosolic precursor of the mitochondrial G3P dehydrogenase. The defect is specific for the G3P dehydrogenase since normal activities of the mitochondrial cytochrome oxidase and succinate dehydrogenase and the cytosolic glycerol dehydrogenase and dihydroxyacetone phosphate reductase are detected in mutant extracts. During attempted growth of glp-2 mutants on glycerol media, there was an accumulation of G3P in culture filtrates, a reduction in the mycelial growth rate, and a decreased level of glycerokinase induction.
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PMID:Isolation and characterization of glycerol-3-phosphate dehydrogenase-defective mutants of Neurospora crassa. 15 57

Plasma membranes were isolated from rat liver mainly under isotonic conditions. As marker enzymes for the plasma membrane, 5'-nucleotidase and (Na+ + K+)-ATPase were used. The yield of plasma membrane was 0.6-0.9 mg protein per g wet weight of liver. The recovery of 5'-nucleotidase and (Na+ +K+)-ATPase activity was 18 and 48% of the total activity of the whole-liver homogenate, respectively. Judged from the activity of glucose-6-phosphatase and succinate dehydrogenase in the plasma membrane, and from the electron microscopic observation of it, the contamination by microsomes and mitochondria was very low. A further homogenization of the plasma membrane yielded two fractions, the light and heavy fractions, in a discontinuous sucrose gradient centrifugation. The light fraction showed higher specific activities of 5'-nucleotidase, alkaline phosphatase, (Na+ +K+)-ATPase and Mg2+-ATPase, whereas the heavy one showed a higher specific activity of adenylate cyclase. Ligation of the bile duct for 48 h decreased the specific activities of (Na2+ +K+)-ATPase and Mg2+-ATPase in the light fraction, whereas it had no significant influence on the activities of these enzymes in the heavy fraction. The specific activity of alkaline phosphate was elevated in both fractions by the obstruction of the bile flow. Electron microscopy on sections of the plasma membrane subfractions showed that the light fraction consisted of vesicles of various sizes and that the heavy fractions contained membrane sheets and paired membrane strips connected by junctional complexes, as well as vesicles. The origin of these two fractions is discussed and it is suggested that the light fraction was derived from the bile front of the liver cell surface and the heavy one contained the blood front and the lateral surface of it.
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PMID:Subfractionation of rat liver plasma membrane. Uneven distribution of plasma membrane-bound enzymes on the liver cell surface. 17 48

16 cases of goiter were examined for C-cells and 4 cases with normal thyroid gland. C-cells identification was based on masked metachromasia. There was stated both in toxic, atoxic goitrous tissue two forms of C-cells. The first characterized by positive metachromatic reaction and weak argyrophinty, the second type of C-cells were orthochromatic and argyrophilic. Metachromatic C-cells characterized as a rule by high alpha glycero phosphate menadione reductase as well succinic dehydrogenase and cytochrome oxidase.
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PMID:Thyroid C-cells in normal and goitrous gland: a histochemical study. 17 26

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

Cell cultures of embryonic calf kidney which had been infected with bovid herpes virus 2 were examined for cytological and histochemical changes. The morphological changes recorded from cells damaged by virus infection included the formation of gigant syncytial cells and intranuclear inclusions of Cowdry Type A. The cytological changes in the infected cells were accompanied by variation in enzyme activity. Recordable were rise in lactate dehydrogenase and alkaline phosphatase as well as decline in succinate dehydrogenase and acid phosphate activity. These phenomena were found to have resulted from impediment of cell metabolism by virus action.
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PMID:[Cytological and histochemical studies on cell cultures infected with bovine herpesvirus type 2]. 18 79


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