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

---

Query: EC:6.4.1.2 (acetyl-CoA carboxylase)
2,876 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fatty acid synthesis was studied in freshly isolated type II pneumocytes from rabbits by 3H2O and (U-14C)-labeled glucose, lactate and pyruvate incorporation and the activity of acetyl-CoA carboxylase. The rate of lactate incorporation into fatty acids was 3-fold greater than glucose incorporation; lactate incorporation into the glycerol portion of lipids was very low but glucose incorporation into this fraction was approximately equal to incorporation into fatty acids. The highest rate of de novo fatty acid synthesis (3H2O incorporation) required both glucose and lactate. Under these circumstances lactate provided 81.5% of the acetyl units while glucose provided 5.6%. Incubations with glucose plus pyruvate had a significantly lower rate of fatty acid synthesis than glucose plus lactate. The availability of exogenous palmitate decreased de novo fatty acid synthesis by 80% in the isolated cells. In a cell-free supernatant, acetyl-CoA carboxylase activity was almost completely inhibited by palmitoyl-CoA; citrate blunted this inhibition. These data indicate that the type II pneumocyte is capable of a high rate of de novo fatty acid synthesis and that lactate is a preferred source of acetyl units. The type II pneumocyte can rapidly decrease the rate of fatty acid synthesis, probably by allosteric inhibition of acetyl-CoA carboxylase, if exogenous fatty acids are available.
...
PMID:De novo fatty acid synthesis by freshly isolated alveolar type II epithelial cells. 613 59

Acetyl-coenzyme A carboxylase has been purified from the plastids of developing castor oil seeds. High concentrations of the enzyme are required for stability as well as the presence of dithiothreitol, glycerol, bicarbonate, Triton X-100, and polyvinyl-pyrrolidone. It has a molecular weight of approximately 528,000 and appears to be membrane associated. Acetyl-CoA carboxylase is active over a wide pH range with an optimum at 8.0. Arrhenius plots are biphasic. The enzyme displays normal Michaelis-Menten kinetics with limiting Michaelis constants of KATP, 0.1 mM; KHCO-3, 3.0 mM; and Kacetyl-CoA, 0.05 mM. Monovalent cations, such as K+ and Cs+, exert a small activating effect on the enzyme while a divalent cation, Mn2+ or Mg2+, is essential for activity. The enzyme does not appear to be highly regulated by cellular metabolites.
...
PMID:Acetyl-coenzyme A carboxylase from the developing endosperm of Ricinus communis. I. Isolation and characterization. 613 95

Preparations of acetyl-CoA carboxylase [acetyl-CoA-carbon-dioxide ligase (ADP-forming), EC 6.4.1.2] have been obtained from the plastids of avocado (Persea americana) fruit mesocarp and from spinach (Spinacia oleracea) chloroplasts. Both preparations required bovine serum albumin, HCO3-, citrate and glycerol for stabilization. The molecular weight of the avocado enzyme was about 6.5 X 10(5) on the basis of 1 mol of biotin/mol of enzyme, the behaviour of both enzymes on gel filtration being in accord with such a value. Removal of the stabilizing bovine serum albumin resulted in the loss of a biotin-containing fragment from the avocado enzyme. Citrate stabilized the enzyme at 10 mM and activated it optimally at 3.0 mM, effecting an approx. 2-fold increase in Vmax. It is suggested that in vivo the enzyme may be located within the chloroplast lamellae.
...
PMID:Acetyl-coenzyme A carboxylase from avocado (Persea americana) plastids and spinach (Spinacia oleracea) chloroplasts. 614 8

Using primary cultures of adult rat hepatocytes, the regulation of the following lipogenic enzymes was studied: glucose-6-phosphate dehydrogenase, malic enzyme, ATP-citrate lyase, acetyl-CoA carboxylase, fatty acid synthetase, and stearoyl-CoA desaturase. The addition to the culture medium of either insulin or triiodothyronine produced a 2-3-fold increase in each of the individual enzyme activities whereas glucagon slightly decreased enzyme activities. The addition to the medium of 8-bromoguanosine 3,'5'-monophosphate had no effect on any of the enzyme activities unless glucose was also added to the culture medium. Glucose addition alone to the culture medium was without any effect; however, glucose enhanced the stimulation of enzyme activity due to insulin. The addition of fructose or glycerol, even in the absence of insulin, increased the activities of each of the enzymes studied 2-3-fold. The increases in enzyme activity brought about by insulin or fructose were apparently the result of de novo enzyme synthesis, as indicated by the observation that the increases were not noted in the presence of cordycepin or cycloheximide. Immunoprecipitation of ATP-citrate lyase from hepatocytes pulse-labeled with [3H]leucine indicated that the induction of this enzyme in response to the addition of fructose or glycerol to the culture medium was the result of an increase in the rate of synthesis of the enzyme. These results indicate that the activity and synthesis of individual enzymes involved in lipogenesis are increased in response to the metabolism of carbohydrate independently in part from hormonal effects.
...
PMID:Induction of lipogenic enzymes in primary cultures of rat hepatocytes. Relationship between lipogenesis and carbohydrate metabolism. 629 23

Saccharin analogues were observed to be potent antihyperlipidemic agents at 20 mg/kg/day in rodents, significantly reducing both serum cholesterol and triglyceride levels in both normal and atherogenic mice. The saccharin analogues suppressed in vitro and in vivo liver enzymatic activity of acetyl-CoA synthetase, citrate lyase, and mitochondrial citrate exchange leading to a reduction of available cytoplasmic acetyl-CoA, which is required for the synthesis of cholesterol and fatty acids. Liver acetyl-CoA carboxylase, phosphatidate phosphohydralase, and glycerol-3-phosphate acyl transferase activities were markedly reduced by the saccharin analogues. Suppression of these enzymes would lead to a reduction of triglyceride synthesis. The saccharin analogues accelerated bile excretion of cholesterol metabolites and increased the fecal excretion of the cholesterol, triglycerides, neutral lipids, and phospholipids. The liver and plasma lipoprotein lipid content (including cholesterol, triglycerides, and neutral lipids) was markedly reduced by the saccharin analogues, whereas phospholipid content was elevated. The reduction of lipid content of serum chylomicron, very low-density, low-density, and high-density lipoprotein fractions by the saccharin analogues indicates that these agents may be useful in controlling hyperlipidemic diseases where specific lipoprotein fractions are elevated.
...
PMID:Antihyperlipidemic activity of saccharin analogues in rodents. 664 71

Subcutaneous adipose tissue samples were obtained by biopsy technique and at slaughter from steers fed either a corn concentrate or pelleted alfalfa (roughage) diet. Steers fed the roughage diet had slightly greater metabolizable energy intakes than the concentrate-fed steers due to greater rates of feed intake; however, steers fed the concentrate diet had faster rates of gain, primarily in the fat depots. Diet had no effect on the incorporation of 14C-labeled acetate and lactate into fatty acids, although 3H2O incorporation into fatty acids was greater in the concentrate-fed steers. Although backfat thickness was 60% greater in the concentrate-fed steers, the number of adipocytes per gram adipose tissue was unaffected by diet, suggesting adipose cell hyperplasia. The activities of acetyl-CoA carboxylase, fatty acid synthetase, ATP citrate lyase, NADP+ malate dehydrogenase, and hexokinase were greater in the steers fed the concentrate diet; pyruvate kinase activity was unaffected by diet. Fatty acid synthesis and several lipogenic enzyme activities increased with age and then declined markedly by the time of the terminal biopsy. Basal and net rates of lipolysis generally were unaffected by diet but increased with age of the animal. As the animals gained weight, the ratio of net fatty acids released to glycerol released decreased, suggesting more extensive reesterification of fatty acids released during lipolysis.
...
PMID:Interrelationships among diet, age, fat deposition and lipid metabolism in growing steers. 669 76

1. The mean volume of adipocytes, the rates of fatty acid and acylglycerol glycerol synthesis from various precursors (in vitro), the rates of oxidation of acetate and glucose (in vitro) and the activities of lipoprotein lipase and various lipogenic enzymes were determined for perirenal adipose tissue from foetal lambs during the last month of gestation. 2. The fall in the rate of growth of perirenal adipose tissue during the last month of gestation is associated with a diminished capacity for fatty acid synthesis and lipoprotein lipase activity, but no change in the rate of acylglycerol glycerol synthesis was observed. There was no fall in the activities of cytosolic acetyl-CoA synthetase or the NADP-linked dehydrogenases, suggesting that the decrease in the rate of fatty acid synthesis was due to an impairment at the level of acetyl-CoA carboxylase or fatty acid synthetase. 3. The rate of fatty acid synthesis from acetate was greater than that from glucose. The rate of fatty acid synthesis from glucose per adipocyte of foetal lambs was similar to that of young sheep. The characteristic metabolism of adipose tissue of the adult sheep is thus present in the foetus, despite the relatively large amounts of glucose in the foetal 'diet'.
...
PMID:Aspects of adipose-tissue metabolism in foetal lambs. 703 12

Intravenous administration of a single dose (100 micrograms/kg bw) of recombinant tumour necrosis factor-alpha (TNF, cachectin) to rats increased the rate of in vitro fatty acid synthesis in interscapular brown adipose tissue (IBAT) from both glucose and alanine, without changes in the oxidation of these substrates to 14CO2. Lactate production and glycerol release were also unaffected by treatment with the cytokine. Additionally, the presence of TNF in the incubation media did not affect fatty acid synthesis, suggesting an indirect effect of the cytokine. The activities of different enzymes of glucose and alanine metabolism such as hexokinase, phosphofructokinase, pyruvate kinase, glucose-6-phosphate dehydrogenase and alanine transaminase, did not suffer changes as a consequence of TNF administration. The same applied to the enzymatic activities involved in fatty acid synthesis such as fatty acid synthase, acetyl-CoA carboxylase and ATP-citrate lyase. Conversely, citrate levels in IBAT were increased in animals treated with TNF, suggesting that it could be the cause for the increased fatty acid synthesis in this tissue.
...
PMID:Metabolic effects of tumour necrosis factor-alpha on rat brown adipose tissue. 759 46

The effects of prolonged (22 weeks) treatment of lactating goats with bovine somatotropin on the metabolism of adipose tissue and liver has been investigated. Somatotropin treatment resulted in smaller adipocytes, decreased rate of fatty acid synthesis and decreased total acetyl-CoA carboxylase activity of adipocytes, but with no change in the proportion of this enzyme in the active state. The rate of acylglycerol glycerol synthesis from glucose of adipocytes tended to decrease as did total glucose utilization by the tissue. Glucose conversion to lactate was unchanged by somatotropin treatment but glucose conversion to other products was decreased. Maximum response of adipose tissue to insulin was unchanged but the sensitivity to insulin decreased on somatotropin treatment. Treatment with somatotropin had no effect on basal lipolysis and decreased maximum response to the beta-agonist isoproterenol, but this probably reflects the rate of isoproterenol-stimulated lipolysis varying with cell volume in adipocytes. No apparent change in response either to alpha 2-adrenergic agonists or to adenosine was apparent. The number of beta-adrenergic receptors was unchanged in adipocyte membranes but the number of alpha 2-adrenergic receptors increased. The rate of hepatic gluconeogenesis in vitro, the activity of key gluconeogenic enzymes and the modulation of the rate of gluconeogenesis by butyrate were unchanged except for the effect of this latter agent on gluconeogenesis from propionate. Hepatic ketogenic activity, as indicated by the activity of carnitine palmitoyl-CoA-transferase-1 and the concentrations of carnitine and acyl carnitines, was unchanged by treatment. Thus at the end of a prolonged period of treatment with somatotropin in lactating goats, lipid synthesis in adipose tissue is still decreased but no effects on liver lipid and carbohydrate metabolism were apparent.
...
PMID:Effects of prolonged treatment of lactating goats with bovine somatotropin on aspects of adipose tissue and liver metabolism. 760 71

The effects of the ingestion of a meal on the partitioning of hepatic fatty acids between oxidation and esterification were studied in vivo for meal-fed rats. The time course for the reversal of the starved state was extremely rapid and the process was complete within 2 h, in marked contrast with the reversal of the effects of starvation in rats fed ad libitum [A. M. B. Moir and V. A. Zammit (1993) Biochem. J. 289, 49-55]. This rapid reversal occurred in spite of the fact that, in the liver of the meal-fed animals before feeding, a similar degree of partitioning of fatty acids in favour of oxidation was observed as in 24 h-starved rats (previously fed ad libitum). This suggested that the lower degree of ketonaemia observed in meal-fed rats before a meal is not due to the inability of acylcarnitine formation to compete successfully with esterification of fatty acids to the glycerol moiety. Investigation of the possible mechanisms that could contribute towards the rapid switching-off of fatty acid oxidation revealed that this was correlated with a very rapid rise and overshoot in hepatic malonyl-CoA concentration, but not with any change in the activity, or sensitivity to malonyl-CoA, of the mitochondrial overt carnitine palmitoyltransferase (CPT I). The role of these two parameters in the reversal of fasting-induced hepatic fatty acid oxidation was thus the inverse of that observed previously for refed 24 h-starved rats. The rapid increase in [malonyl-CoA] was accompanied by an immediate and complete reversion of the kinetic characteristics (Ka for citrate, expressed/total activity ratio) of acetyl-CoA carboxylase to those found in the post-meal animals, again in contrast with the time course observed in refed 24 h-starved rats [A. M. B. Moir and V. A. Zammit (1990) Biochem. J. 272, 511-517]. The rapidity with which these changes occurred was specific to the partitioning of acyl-CoA; the meal-induced diversion of glycerolipids towards phospholipid synthesis and the acute inhibition of the fractional rate of triacylglycerol secretion occurred with very similar time courses to those observed upon refeeding of 24 h-starved rats. The results confirm the central role played by differences in the dynamics of changes in hepatic malonyl-CoA concentration, and CPT I sensitivity to it, in determining the route through which ingested glucose is converted into hepatic glycogen upon refeeding of starved rats which had previously been meal-fed or fed ad libitum.
...
PMID:Rapid switch of hepatic fatty acid metabolism from oxidation to esterification during diurnal feeding of meal-fed rats correlates with changes in the properties of acetyl-CoA carboxylase, but not of carnitine palmitoyltransferase I. 809 87


<< Previous 1 2 3 4 5 6 7 8 9 Next >>

---