Showing papers on "ATP citrate lyase published in 1987"
TL;DR: It is shown that the enzyme mediating citrate formation is an ATP-citrate lyase (EC 4.1.3.8) rather than a citrate synthase, which enables D. postgatei to couple the oxidation of acetate to 2 CO2 with the net synthesis of ATP via substrate level phosphorylation.
Abstract: Desulfobacter postgatei is an acetate-oxidizing, sulfate-reducing bacterium that metabolizes acetate via the citric acid cycle. The organism has been reported to contain a si-citrate synthase (EC 4.1.3.7) which is activated by AMP and inorganic phosphate. It is show now, that the enzyme mediating citrate formation is an ATP-citrate lyase (EC 4.1.3.8) rather than a citrate synthase. Cell extracts (160,000xg supernatant) catalyzed the conversion of oxaloacetate (apparent K
m=0.2 mM), acetyl-CoA (app. K
m=0.1 mM), ADP (app. K
m=0.06 mM) and phosphate (app. K
m=0.7 mM) to citrate, CoA and ATP with a specific activity of 0.3 μmol·min-1·mg-1 protein. Per mol citrate formed 1 mol of ATP was generated. Cleavage of citrate (app. K
m=0.05 mM; V
max=1.2 μmol · min-1 · mg-1 protein) was dependent on ATP (app. K
m=0.4 mM) and CoA (app. K
m=0.05 mM) and yielded oxaloacetate, acetyl-CoA, ADP, and phosphate as products in a stoichiometry of citrate:CoA:oxaloacetate:ADP=1:1:1:1. The use of an ATP-citrate lyase in the citric acid cycle enables D. postgatei to couple the oxidation of acetate to 2 CO2 with the net synthesis of ATP via substrate level phosphorylation.
55 citations
TL;DR: In kinetic experiments, the activation of malate dehydrogenase by citrate synthase was observed, and the effect of pyridine nucleotides and alpha-ketoglutarate is discussed in relation to the direction of the metabolic flow of oxalacetate.
48 citations
TL;DR: The regulation of anaerobic citrate metabolism is very diverse among different groups of bacteria as discussed by the authors and there are many anaerobes like Rhodocyclus gelatinosus and Clostridium sphenoides which contain citrate synthase.
Abstract: The regulation of anaerobic citrate metabolism is very diverse among different groups of bacteria. In organisms like Streptococcus lactis and Clostridium sporosphaeroides which lack citrate synthase, the activity of its antagonistic enzyme, citrate lyase, need not be regulated. Many anaerobes like Rhodocyclus gelatinosus and Clostridium sphenoides are able to synthesize their own L-glutamate and contain citrate synthase. In these bacteria the activity of citrate metabolizing enzymes which are involved in a cascade system are under strict control. In Rc. gelatinosus activation/inactivation of citrate lyase is controlled by acetylation/deacetylation which is catalyzed by its corresponding regulatory enzymes, citrate lyase ligase and citrate lyase deacetylase. In C. sphenoides inactivation of citrate lyase is accomplished by deacetylation as well as by changing in the enzyme conformation. Activation of citrate lyase is catalyzed by citrate lyase ligase whose activity in addition is modulated by phosphorylation/dephosphorylation. Further, electron transport process also seems to play a role in the inactivation of citrate metabolizing enzymes in enteric bacteria.
36 citations
TL;DR: A method involving fast protein liquid anion exchange chromatography was developed in order to obtain enzyme preparations sufficiently free of enzymes which could interfere with kinetic investigations to identify ATP:citrate lyase in cell-free extracts from the filamentous fungus Aspergillus niger.
Abstract: ATP:citrate lyase (EC 4.1.3.8) has been identified in cell-free extracts from the filamentous fungus Aspergillus niger. The enzyme was located in the cytosol. It exhibits an activity at least ten times that of acetate-CoA-kinase (EC 6.2.1.1) during growth on carbohydrates as carbon sources, and is thus considered responsible for acetyl-CoA formation under these conditions. It is formed constitutively and its biosynthesis does not appear to be controlled by changes in the nitrogen or carbon source or type. ATP:citrate-lyase appears to be very labile during conventional purification procedures; a method involving fast protein liquid anion exchange chromatography was thus developed in order to obtain enzyme preparations sufficiently free of enzymes which could interfere with kinetic investigations. This preparation displays commonly known characteristics of ATP:citrate lyase with respect to substrate affinities and cofactor requirements, with the exception that the affinity for citrate is rather low (2.5 mM). No activator was found. The enzyme is inhibited by nucleoside diphosphates, nucleoside monophosphates and palmitoyl-CoA. Regulation of ATP:citrate lyase be the energy charge of the cytosol in relation to lipid or citric acid accumulation is discussed in view of these findings.
34 citations
TL;DR: The metabolism of citrate in P. halophilus was different from that observed in lactic streptococci, and the main products from citrate were acetate and formate, and this bacterium produced no acetoin or diacetyl.
Abstract: Several strains of non-citrate-metabolizing Pediococcus halophilus have previously been isolated from soy sauce mash or moromi The factors controlling the metabolism of citrate in soy pediococci were studied All the soy pediococcal strains tested which failed to decompose citrate did not possess citrate lyase [citrate (pro-3S)-lyase; EC 4136] activity In P halophilus, citrate lyase was an inducible enzyme, and the optimum pH for activity was 70 The metabolism of citrate in P halophilus was different from that observed in lactic streptococci The main products from citrate were acetate and formate, and this bacterium produced no acetoin or diacetyl Formate production from citrate was greatly reduced in the presence of glucose P halophilus 7117 (Cit+) was proved to contain citrate lyase, pyruvate formate-lyase (EC 23154) phosphotransacetylase (phosphate acetyltransferase; EC 2318), and acetate kinase (EC 2721), ie, all the enzymes necessary to convert citrate to acetate and formate
25 citations
TL;DR: It is demonstrated that the beta-adrenergic agonist isoproterenol or insulin both promote an immobilization of ATP citrate-lyase, detected in digitonin-permeabilized adipocytes, and suggested that the state of phosphorylation in adipocytes controls the localization in the cell.
17 citations
TL;DR: Using high-pressure liquid chromatography, it was possible to demonstrate that the reported large acyl carrier protein was a contaminating protein associated with citrate lyase multienzyme complex; it could be removed by anion-exchange chromatography with Q-Sepharose.
17 citations
TL;DR: In this paper, the authors showed that the addition of 1 mm Cu2+ ions had no effect on citrate uptake activity or diacetyl reductase activity, while adding Cu2 +, Fe2+, Fe3+ and Mo6+ ions to the reaction mixture increased the amount of dacetyl formation activity of the cells.
Abstract: Streptococcus lactis subsp. diacetylactis 3022 produced 5.4 times the amount of diacetyl on 24 hours incubation in 30% RSM medium supplemented with 1 mm Cu2 +, compared to that in the medium without Cu2 +. However, the citrate utilization in the medium with Cu2+ was considerably repressed. On the other hand, the diacetyl formation activity of the cells was markedly stimulated by adding Cu2 +, Fe2 +, Fe3 +, Co2+ and Mo6+ to the reaction mixture. Cu2+ and Co2+ also stimulated citrate lyase. Cu2+ was the most effective stimulator for these activities. These metal ions had no effects on citrate uptake activity or diacetyl reductase activity.After the addition of MRS medium with and without Cu2+ to a culture incubated at 30°C for 24 hours, the cells in the medium with Cu2 + produced.a larger amount of diacetyl than those in the medium without Cu2 +. On the contrary, the citrate utilization of the former cells was inferior to that of the latter. From these results, it appeared that diacetyl reductase activity w...
15 citations
TL;DR: Differences in intracellular enzyme activities between cells accumulating lipid and proliferating cells were studied with Lipomyces starkeyi, a fat‐producing yeast.
Abstract: Differences in intracellular enzyme activities between cells accumulating lipid and proliferating cells were studied with Lipomyces starkeyi, a fat-producing yeast. When the cells were removed from a medium for lipid accumulation to a medium for cell proliferation, activities of several enzymes on the glycolytic pathway, pentosephosphate cycle, glycerol 3-phosphate pathway, tricarboxylic acid cycle and fatty-acid biosynthesis pathway changed. In the proliferating cells, activities of glycerol-3-phosphate dehydrogenase (GDH) and ATP citrate lyase were very low, as compared to those in the cells accumulating lipids. Activities of these two enzymes and 6-phosphogluconate dehydrogenase, particularly GDH, decreased with the addition of zinc ion to the cell-free extract of the cells accumulating lipid.
14 citations
TL;DR: In vivo fatty acid synthesis and the in vitro activity of the enzymes fatty acid synthase, ATP citrate lyase, glucose 6-phosphate dehydrogenase were examined in the livers of rats fed fat free, high carbohydrate (HC) diet or those fed diets containing 44% calories from either corn oil or hydrogenated soybean oil.
9 citations
TL;DR: The half maximal effect on the enzyme determined in hepatocytes incubated with TGF-β for 10 min at 37°C was elicited by T GF-β concentrations in the 10−11 – 10−12 M range.
Abstract: Transforming growth factor beta (TGF-β) activates ATP citrate lyase in freshly isolated rat liver hepatocytes in a time dependent manner. Maximal stimulation of the enzyme occurred with less than thirty minutes of incubation of the cells with TGF-β. The half maximal effect on the enzyme determined in hepatocytes incubated with TGF-β for 10 min at 37°C was elicited by TGF-β concentrations in the 10−11 – 10−12 M range. The potential role of TGF-β stimulation of ATP citrate lyase activity in new membrane synthesis is discussed.
TL;DR: The activities of two enzymes involved in the lipogenic process, ATP citrate lyase and NADP-linked malic enzyme were evaluated as a function of cell density in isolated rat hepatocytes and profoundly affected by cell density.
TL;DR: It is shown that phosphorylation has no significant effect on the fraction of the enzyme that may be bound to isolated mitochondria, and cyclic AMP‐dependent protein kinase is used as a substrate for this enzyme.
01 Jan 1987
TL;DR: To determine whether the acetono-group would interfere with CoA biosynthesis, a crude preparation of the bifunctional enzyme complex which converts ATP and pantetheine 4’-phosphate to CoA was investigated.
Abstract: The synthetic acetyl-CoA analog, acetono-CoA (acetonyldethiocoenzyme A), in which the sulfur atom has been replaced by a methylene group, has been previously synthesized and found to be a competitive inhibitor (KI= 13.2 µM) of acetyl-CoA with citrate synthase. To determine whether the acetono-group would interfere with CoA biosynthesis, a crude preparation of the bifunctional enzyme complex which converts ATP and pantetheine 4’-phosphate to CoA was investigated. Incubation mixtures of the crude complex, ATP, and acetonyldethio-pantetheine 4’-phosphate were prepared. Products and reactants were isolated by DEAE-cellulose column chromatography and peaks were identified by TLC. Enzymatic synthesis of acetono-CoA was verified by establishing its KI (25 µM) in the citrate synthase reaction.
01 Jan 1987
TL;DR: Regulation of specific gene expression in the liver is a dynamic process, far more complex than heretofore suspected, and a much greater contribution of posttranscriptional regulation accounts for changes in expression of genes representing major functions of the liver.
Abstract: transferrin, and cytochrome P450, TF-1) and post-transcriptional control (a~-acid glycoprotein, apolipoproteins A-1 and E, malic enzyme, and ATP citrate lyase), as well as "mixed" regulation (ligandin and cytochrome P450, RI7). Examples have been identified in which the predominant mode for regulating expression of preferentially expressed genes changes from transcriptional to post-transcriptional at different stages of liver development and some members of multigene families (cytochrome P450s and apolipoprotein genes) also show independent and sometimes contrasting modes of regulation. Therefore, it appears that regulation of specific gene expression in the liver is a dynamic process, far more complex than heretofore suspected, and a much greater contribution of posttranscriptional regulation accounts for changes in expression of genes representing major functions of the liver.