Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q8NEX9 (reductase)
 26,410 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A particulate fraction prepared from Mycobacterium phlei grown in a metal-deficient medium exhibited a greatly reduced activity of stearoyl-CoA desaturase compared to that from normally grown cells. Metal deficiency, however, had no effect on the FAD-dependent NADPH-cytochrome C reductase activity, which has been suggested to participate in the desaturation process. When the cells were grown in the deficient medium supplemented with both Fe2+ and Mg2+, the desaturase activity was restored to the normal level. Supplementation with Mg2+ alone promoted growth but did not restore the desaturase activity, whereas Fe2+ alone did cause a significant restoration. Among the various metal ions tested, only Fe2+ and Fe3+ enhanced the formation of desaturase activity in the deficient medium. When added to the assay medium in vitro, Fe2+ and Fe3+ did not stimulate the desaturase activity of the particulate fraction from the deficient cells. Cultivation in the metal-deficient medium had essentially no effect on the levels of cytochromes in the particulate fraction, but dramatically decreased the non-heme iron content and the amount of a high-spin ferric species exhibiting an ESR signal at g=4.3. No labile sulfur could be detected in the normal or metal-deficient particulate fractions. It is concluded that the presence of iron ions in the culture medium is necessary for the synthesis and/or assembly of the terminal portion of the desaturase system.
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PMID:Effect of metal ions in the culture medium on the stearoyl-coenzyme A desaturase activity of Mycobacterium phlei. 0 87

1. Rat liver microsomal stearoyl-CoA desaturase activity was shown to be stimulated by both bovine serum albumin and a basic cytoplasmic protein from rat liver. 2. Partially purified desaturase is unaffected by either of these two proteins. 3. Bovine serum albumin appears to exert its effect on the crude system by protecting the desaturase substrate, stearoly-CoA, from the action of endogenous thiolesterases. 4. By using partially purified enzyme preparations, it was possible to establish the substate specificity of the delta9-fatty acyl-CoA desaturase with the C14, C15, C16, C17, C18 and C19 fatty acyl-CoA substrates. Maximum enzyme activity was shown with stearoyl-CoA decreasing with both palmitoyl-CoA and nonadecanoyl-CoA, as reported previously for free fatty acids. 5. Both cytochrome b5 and NADH-cytochrome b5 reductase (EC 1.6.2.2) are required for these studies and a method is described for the purification of homogeneous preparations of detergent-isolated cytochrome b5 from rat liver. 6. From amino acid analyses, a comparison was made of the hydrophobicity of the membrane portion of cytochrome b5 with the hydrophobicity reported for stearoyl-CoA desaturase. The close resemblance of the two values suggested that unlike cytochrome b5 and its reductase, the stearoyl-CoA desaturase may be largely buried in the endoplasmic reticulum.
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PMID:Properties of rat liver microsomal stearoyl-coenzyme A desaturase. 1 47

The effect of 28-day ethanol consumption on hamster liver microsomal electron transport systems and associated enzymatic activities has been examined. Microsomes isolated from ethanol-consuming hamsters showed increased levels of cytochrome P-450 and NADPH supported enzymatic activities. In contrast, reductions in the amount of cytochrome b5 and the NADH-supported rate of stearoyl-CoA desaturase were observed. NADH-cytochrome c reductase was decreased while a small increase in NADH-ferricyanide reductase was observed. These data suggest that decreased stearoyl-CoA desaturase activity is the result of lowered cytochrome b5 levels in microsomes isolated from ethanol-consuming hamsters.
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PMID:Differential effect of ethanol consumption on hamster liver microsomal electron transport systems. 286 Aug 17

The effect of local anesthetics on the stearoyl-CoA desaturase activity was studied using Tetrahymena microsomal preparation. Dibucaine, tetracaine, and propranolol, a beta-blocking agent, nonspecifically inhibited the activities of NADPH-ferrihemoprotein reductase as well as of stearoyl-CoA desaturase and the terminal component, but lidocaine and procaine had no effect on these activities. The inhibitory potency was decreased in the order of dibucaine greater than propranolol greater than tetracaine much greater than lidocaine = procaine. According to the double-reciprocal plots of stearoyl-CoA desaturase, the inhibition by dibucaine appeared to be noncompetitive with respect to stearoyl-CoA as substrate. However, the activity of NADH-ferricyanide reductase was not significantly affected by concentrations of propranolol and tetracaine lower than 10mM, but by dibucaine. The terminal component, cyanide-sensitive factor, was most sensitive to local anesthetics among the microsomal electron transport components, suggesting a rate-limiting enzyme.
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PMID:Effect of local anesthetics on stearoyl-CoA desaturase of Tetrahymena microsomes. 286 69

Stearoyl-CoA desaturase activity in microsomes from lactating rat mammary gland is very low (0.05-0.15 nmol/min/mg of protein) regardless of lactating time. In such microsomes, reductase activities and content of cytochrome b5 are several-fold lower than in normal rat liver microsomes. Preincubation of the mammary microsomes with purified terminal desaturase gives a 55-fold stimulation of stearoyl-CoA desaturase activity, whereas preincubation with cytochrome b5 has no effect. However, preincubation of mammary microsomes with both cytochrome b5 and terminal desaturase results in a 200-fold stimulation of overall desaturation. These observations suggest that negligible stearoyl-CoA desaturase activity in lactating rat mammary microsomes is due to a cytochrome b5 content and the absence of terminal enzyme. The hepatic stearoyl-CoA desaturase activity increases 9-fold during lactation. There is little or no change in the NADH-cytochrome c reductase activity or in the concentrations of cytochrome b5 during this period, but the activity of the terminal desaturase increases with the increase of overall desaturation. These results suggest that liver is one of the more important sources of oleic acid for milk triglycerides.
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PMID:Stearoyl-coenzyme A desaturase activity in the mammary gland and liver of lactating rats. 612 66

1. Microsomes were isolated from rabbit fast-twitch and slow-twitch muscle and were separated into heavy and light fractions by centrifugation in a linear (0.3-2m) sucrose density gradient. The membrane origin of microsomal vesicles was investigated by studying biochemical markers of the sarcoplasmic-reticulum membranes and of surface and T-tubular membranes, as well as their freeze-fracture properties. 2. Polyacrylamide-gel electrophoresis showed differences in the Ca(2+)-dependent ATPase/calsequestrin ratio between heavy and light fractions, which were apparently consistent with their respective origin from cisternal and longitudinal sarcoplasmic reticulum, as well as unrelated differences, such as peptides specific to slow-muscle microsomes (mol.wts. 76000, 60000, 56000 and 45000). 3. Freeze-fracture electron microscopy of muscle microsomes demonstrated that vesicles truly derived from the sarcoplasmic reticulum, with an average density of 9nm particles on the concave face of about 3000/mum(2) for both fast and slow muscle, were admixed with vesicles with particle densities below 1000/mum(2). 4. As determined in the light fractions, the sarcoplasmic-reticulum vesicles accounted for 84% and 57% of the total number of microsomal vesicles, for fast and slow muscle respectively. These values agreed closely with the percentage values of Ca(2+)-dependent ATPase protein obtained by gel densitometry. 5. The T-tubular origin of vesicles with a smooth concave fracture face in slow-muscle microsomes is supported by their relative high content in total phospholipid and cholesterol, compared with the microsomes of fast muscle, and by other correlative data, such as the presence of (Na(+)+K(+))-dependent ATPase activity and of low amounts of Na(+)-dependent membrane phosphorylation. 6. Among intrinsic sarcoplasmic-reticulum membrane proteins, a proteolipid of mol.wt. 12000 is shown to be identical in the microsomes of both fast and slow muscle and the Ca(2+)-dependent ATPase to be antigenically and catalytically different, though electrophoretically homogeneous. 7. Basal Mg(2+)-activated ATPase activity was found to be high in light microsomes from slow muscle, but its identification with an enzyme different from the Ca(2+)-dependent ATPase is still not conclusive. 8. Enzyme proteins that are suggested to be specific to slow-muscle longitudinal sarcoplasmic reticulum are the flavoprotein NADH:cytochrome b(5) reductase (mol.wt. 32000), cytochrome b(5) (mol.wt. 17000) and the stearoyl-CoA desaturase, though essentially by criteria of plausibility.
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PMID:Biochemical heterogeneity of skeletal-muscle microsomal membranes. Membrane origin, membrane specificity and fibre types. 628 27

Tetrahymena ISO cells, which have an unusually high level of iso odd-numbered fatty acids, were grown medium supplemented with various concentrations of isovalerate. There was a marked increase in the total proportion of iso odd-numbered fatty acids in supplemented whole cells (28.9 leads to 70.3%) and microsomes (37.7 leads to 84%), with a corresponding decrease in normal fatty acids, although no significant alteration of phospholipid composition was observed during 11 hr isovalerate-supplementation. Microsomal palmitoyl-CoA and stearoyl-CoA desaturase activities in isovalerate-supplemented cells decreased by 45.7% and 30.6% during 11 hr, respectively. NADH-cytochrome c reductase and NADH-ferricyanide reductase activities as well as the content of cytochrome b560ms, which is similar to mammalian microsomal cytochrome b5, were reduced in microsomes from 11 hr-supplemented cells, whereas NADPH-cytochrome c reductase activity was constant. It is suggested that the alteration of the cross-sectional area of lipid molecules in the bilayer, which results from the replacement of normal fatty acids with iso- 15:0 and iso- 17:1, would result in the decline of palmitoyl- and stearoyl-CoA desaturation in the isovalerate-supplemented cells, in order to maintain membrane fluidity at a functional level.
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PMID:Modification of microsomal lipid composition and electron transport enzyme activities in isovalerate-supplemented cells of novel Tetrahymena ISO. 641 Jan 44

Tetrahymena microsomes were solubilized with five different detergents and the effect on electron transport enzymes involved in fatty acid desaturation was studied. Cytochrome b560ms and NADPH-cytochrome c reductase were solubilized with a low concentration detergent (0.25%), in the order of sodium deoxycholate greater than Renex 690 greater than Triton X-100 greater than octylglucoside greater than sodium cholate, whereas all of these detergents at the high concentration (1%) could solubilize preferentially both enzymes (70-100%). Increasing the concentration of various detergents from 0.5 to 1.0% did not produce an incremental change in NADH-ferricyanide reductase solubilization. NADH-cytochrome c reductase system, which would be catalyzed by the cooperation action of NADH-ferricyanide and cytochrome b560ms, was relatively inactivated by all detergents. Compared to the other four detergents, octylglucoside has a much higher recovery of stearoyl-CoA desaturase activities in the supernatant. Our study suggests that octylglucoside may be more useful for the isolation in active form of cyanide-sensitive factor (CSF) from Tetrahymena microsomes.
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PMID:Studies on Tetrahymena microsomal electron transport systems: solubilization of microsomal electron transport enzymes involved in fatty acid desaturation. 643 62

Recent studies have shown that dietary oxidised fats influence the lipid metabolism in rats by activation of PPARalpha. In this study, we investigated whether a mildly oxidised fat causes activation of PPARalpha in pigs which are non-proliferators like man. Eighteen pigs were assigned to two groups and received either a diet containing 90 g/kg of a fresh fat or the same diet with 90 g/kg of an oxidised fat prepared by heating for 24 h at 180 degrees C in a deep fryer. Pigs fed the oxidised fat had a higher peroxisome count, a higher activity of catalase and a higher mRNA concentration of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase in the liver and a higher concentration of 3-hydroxybutyrate in plasma than pigs fed the fresh fat (P< 0.05). Hepatic mRNA concentrations of acyl-CoA oxidase and carnitine palmitoyltransferase- 1 tended to be increased in pigs fed the oxidised fat compared to pigs fed the fresh fat (P< 0.10). Pigs fed the oxidised fat, moreover, had higher mRNA concentrations of sterol regulatory element-binding protein (SREBP)-1 and its target genes acetyl-CoA carboxylase and stearoyl-CoA desaturase in the liver and higher mRNA concentrations of SREBP-2 and its target genes 3-hydroxy-3-methylglutary-CoA reductase and LDL receptor in liver and small intestine. In conclusion, this study shows that even a mildly oxidised fat causes activation of PPARalpha in the liver of pigs. Up-regulation of SREBP and its target genes in liver and small intestine suggests that the oxidised fat could stimulate synthesis of cholesterol and TAG in these tissues.
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PMID:Feeding of a deep-fried fat causes PPARalpha activation in the liver of pigs as a non-proliferating species. 1738 80

1. This study investigates the enzymatic reduction of N-hydroxylated amidines by porcine adipose tissue and the possible involvement of stearoyl-CoA desaturase (SCD). 2. The reduction of the model substrate benzamidoxime was studied with porcine adipose tissue microsomes and partially purified SCD from SCD-enriched rat liver microsomes. 3. Inhibitor studies with these microsomal preparations using various inhibitors including anti-SCD antibody, cyanide and stearoyl-CoA supported a role for SCD in the reduction of N-hydroxylated amidines in adipose tissue. The content and activity of SCD in these microsomes was established by Western blot and SCD activity determinations. Additionally, a reconstituted system of cytochrome b(5), NADH-cytochrome b(5) reductase and partially purified SCD from SCD-enriched rat liver microsomes supported benzamidoxime reductase activity that was inhibitable by an anti-SCD antibody. 4. The results support the participation of SCD in the reduction of amidoxime prodrugs and demonstrate for the first time that SCD can also accept foreign compounds (xenobiotics) as substrates.
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PMID:Involvement of stearoyl-CoA desaturase in the reduction of amidoxime prodrugs. 1860 46


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