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)

A rapid switch from a fermentative to a primarily oxidative type of glucose utilization was observed during in vitro differentiation of Trypanosoma brucei STIB348 and EATRO1244 bloodstream to procyclic trypomastigotes. In accordance with previously published reports bloodstream populations produced pyruvate as the major end product of glucose catabolism, together with very small amounts of CO2, succinate and glycerol. During differentiation pyruvate excretion decreased within 48 h to the low levels produced by 28-day procyclic stages. Concomitant with the decline in pyruvate formation, acetate appeared as a new product and the rates of respiratory CO2 increased considerably. The amount of carbon released with these compounds could account for nearly all of the glucose carbon consumed. Rates of glucose utilization and formation of acetate and CO2 in cells differentiated for 48 h were essentially the same as those found in 28-day procyclics. Succinate and glycerol excretion remained low during the entire transformation process, and no significant difference in the pattern and quantities of end products were found between the two trypanosome strains. During trypanosome differentiation the changes in metabolism were associated with marked alterations in enzyme activity levels. Activities of the tricarboxylic acid (TCA) cycle enzymes citrate synthase, isocitrate dehydrogenase (NAD+), succinate dehydrogenase and fumarase were not detectable in bloodstream trypomastigotes but appeared upon differentiation for 24 h. An exception was citrate synthase whose activity was not demonstrable until 48 h postinoculation into culture. After 48 h the majority of the TCA cycle enzyme activities continued to increase steadily until day 28. Pyruvate kinase activity decreased in differentiating cells after 48 h to about 25% of the level found in bloodstream trypomastigotes.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Alterations in Krebs cycle enzyme activities and carbohydrate catabolism in two strains of Trypanosoma brucei during in vitro differentiation of their bloodstream to procyclic stages. 190 88

The contribution of muscle tissue to the increased metabolic efficiency of the obese (fa/fa) Zucker rat at 6 wk of age was examined. In vitro O2 consumption was similar in obese and nonobese soleus and extensor digitorum longus (EDL) muscles, whether the animals were fed ad libitum, fasted, or treated with triiodothyronine. No phenotypic difference in the in vitro O2 consumption was seen when the muscles were preincubated with or without exogenous insulin. Pyruvate kinase, citrate synthase, succinate dehydrogenase, and cytochrome oxidase activities were similar in the soleus and the EDL muscles of both phenotypes. Phosphofructokinase and lactate dehydrogenase activities were higher in the soleus muscles from the obese rats, whereas hexokinase activities were higher in the EDL muscles from the nonobese rats. Mitochondrial and whole muscle homogenate respiration rates were similar in both phenotypes. The soleus and EDL muscles from the obese animals weighed less than those from the nonobese, but empty carcass weights were similar. Taken together these data suggest that muscle mass, muscle O2 consumption, and muscle oxidative capacity are similar in 6-wk-old obese and nonobese rats. Therefore other tissues are probably responsible for the increased metabolic efficiency of the young obese rat.
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PMID:Oxygen consumption and oxidative capacity of muscles from young obese and nonobese Zucker rats. 609 7

Histochemical analysis of five muscles from the water monitor, Varanus salvator, identified three major classes of fibers based on histochemical activities of the enzymes myosin ATPase (mATPase), succinic dehydrogenase (SDH), and alpha-glycerophosphate dehydrogenase (alpha GPDH). Fast-twitch, glycolytic (FG) fibers were the most abundant fiber type and exhibited the following reaction product intensities: mATPase, dark; SDH, light; alpha GPDH, moderate to dark. Fast-twitch, oxidative, glycolytic (FOG) fibers were characteristically mATPase, dark; SDH, light; alpha GPDH, moderate to dark. The third class of fibers had the following histochemical characteristics: mATPase, light; SDH, moderate to dark; alpha GPDH, light. These fibers were considered to be either slow twitch, or tonic, and oxidative (S/O). Pyruvate kinase (PK), alpha GPDH, and citrate synthase (CS) activities were measured in homogenates of the same muscles studied histochemically. There was a positive relationship between both PK and alpha GPDH activities and the percentage of glycolytic fiber types within a muscle. Likewise, CS activities were greater in muscles high in FOG and S/O content. Based on CS activities, Varanus S/O fibers were eight-fold more oxidative than FG fibers within the same muscle. PK/CS ratios suggested that FG fibers possess high anaerobic capacity, similar to the iguanid lizard Dipsosaurus. The fiber type composition of the gastrocnemius muscle, relative to that of other lizard species, suggests that varanid lizards may possess a greater proportion of FOG and S/O fibers than other lizards.
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PMID:A histochemical and enzymatic study of the muscle fiber types in the water monitor, Varanus salvator. 622 35

The photosensitizing activity of hematoporphyrin derivative (HPD) was investigated by studying selected enzymes localized to mitochondria and cytosol of R3230AC mammary adenocarcinomas. Experiments in vitro demonstrated that mitochondrial succinate dehydrogenase was inhibited in a drug dose- and light exposure time-related manner; at 7.0 micrograms of HPD per ml or higher, enzyme activity was inhibited greater than 50% after 15 min of photoradiation. The three cytosol enzymes studied under the same conditions in vitro demonstrated different photosensitivities. Pyruvate kinase activity was significantly inhibited in a dose- and time-related fashion, whereas lactate dehydrogenase was inhibited to a lesser extent, and glucose phosphate isomerase activity was inhibited only at the highest dose (70 micrograms of HPD per ml) used. The time-course of these responses was examined with an in vivo-in vitro protocol, consisting of photoradiation of mitochondria and cytosol prepared from tumors obtained at various times (up to 1 week) after a single injection of HPD (80 mg/kg). Pyruvate kinase activity was markedly inhibited at early times returning to initial levels by 48 hr; neither lactate dehydrogenase nor glucose phosphate isomerase was inhibited by this treatment. Mitochondrial succinate dehydrogenase and cytochrome c oxidase activities displayed significant photoradiation-induced inhibitions, with greatest inhibition occurring between 24 and 96 hr after injection of HPD; at 1 week, succinate dehydrogenase activity had returned to its initial level, but cytochrome c oxidase activity remained significantly inhibited. These data suggest that HPD-induced photosensitization of mitochondria may be an important site of action contributing to tumor cell cytotoxicity and regression as a result of photoradiation therapy.
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PMID:Hematoporphyrin derivative-induced photosensitivity of mitochondrial succinate dehydrogenase and selected cytosolic enzymes of R3230AC mammary adenocarcinomas of rats. 623 Oct 99

Since chronic stress has been used widely for studying clinical depression and that brain energy metabolism and oxidative stress might be involved in the pathophysiology of this illness, the objective of this study was investigate the activities of pyruvate kinase, complex II and IV (cytocrome c oxidase) in hippocampus and prefrontal cortex of rats submitted to chronic variable stress. We also evaluated if vitamins E and C administration could prevent such effects. During 40 days adult rats from the stressed group were subjected to one stressor per day, at a different time each day, in order to minimize predictability. The stressed group had gained less weight while its immobilization time in the forced swimming test was greater than that of the control group. Results showed that stressed group presented an inhibition in the activities of complex II and cytochrome c oxidase in prefrontal cortex, while in hippocampus just complex IV was inhibited. Pyruvate kinase activity was not altered in stressed group when compared to control. Vitamins E and C administration prevented the alterations on respiratory chain caused by stress. These data suggest that the impairment of energy metabolism and oxidative stress could be related with the pathogenic pathways in stress related disorders.
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PMID:Chronic variable stress impairs energy metabolism in prefrontal cortex and hippocampus of rats: prevention by chronic antioxidant treatment. 2050 86