scholarly journals The Pyruvate Carboxylase of Verticillium albo-atrum

Microbiology ◽  
2000 ◽  
Vol 81 (1) ◽  
pp. 15-19 ◽  
Author(s):  
R. E. Hartman ◽  
N. T. Keen
Keyword(s):  
Pyruvate Carboxylase ◽  
Krebs Cycle ◽  
Physiological Role ◽  
Maximum Activity ◽  
Ph Optimum ◽  
Carboxylase Activity ◽  
Metabolic Intermediates ◽  
Krebs Cycle Intermediates ◽  
Verticillium Albo Atrum

The pyruvate carboxylase of Verticillium albo-atrum had a pH optimum of 7·8 and a specific requirement for ATP. At the optimum pH, magnesium ions were required for maximum activity, while at pH 6·8 manganese was more effective than magnesium. Potassium was stimulatory while sodium was ineffective. Avidin and p-chloromercuribenzoate strongly inhibited the enzyme while biotin and dithiothreitol, respectively, reversed the effect of the inhibitors. Aspartate and oxalacetate were inhibitory while acetyl-CoA and CoA reversed the inhibition by aspartate. These cofactors were ineffective in the absence of aspartate. None of the tested metabolic intermediates was stimulatory to pyruvate carboxylase activity while NADP+ and 2,3-diphosphoglycerate were the most effective inhibitors (75%) at a concentration of 6·7 mM. Levels of pyruvate carboxylase in cells grown on glucose, acetate, malate, xylose, glycerol or aspartate differed only slightly. The data indicated that the physiological role of pyruvate carboxylase in V. albo-atrum is the anaplerotic biosynthesis of C4 Krebs-cycle intermediates from pyruvate.

The influence of biotin on viability, pyruvate carboxylase activity and the response to malate concentration in vitro by isolated secondary hair follicles of the Angora goat

1999 ◽  
Vol 1999 ◽  
pp. 158-158
Author(s):  
A.M. Tahmasbi ◽  
H. Galbraith ◽  
J.R. Scaife
Keyword(s):  
Pyruvate Carboxylase ◽  
Krebs Cycle ◽  
Hair Follicles ◽  
Prosthetic Group ◽  
Biotin Deficiency ◽  
Carboxylase Activity ◽  
Poor Growth ◽  
Krebs Cycle Intermediates ◽  
Biotin Supplementation

Biotin is a prosthetic group for a number of enzymes involved in carboxylation reactions. Biotin deficiency has been associated with poor growth of integumental tissues by currently unknown mechanisms. Pyruvate carboxylase is a biotin-dependent enzyme which has an important anaplerotic role in intermediary metabolism, catalysing the formation of oxaloacetate from pyruvate and bicarbonate. It thus provides oxaloacetate for gluconeogenesis and replenishes Krebs cycle intermediates. Biotin deficiency may reduce pyruvate carboxylase activity and so oxaloacetate production. Malate is a Krebs cycle intermediate which can convert to oxaloacetate and reduce demand for oxaloacetate generated by pyruvate carboxylase. The aims of the study were to determine (a) the effect of biotin supplementation of the medium on hair follicle viability and pyruvate carboxylase activity and (b) the response to supplementation of the culture medium with malate.

Role of salicylic acid in regulation of cadmium toxicity in wheat ( Triticum aestivum L.)

2009 ◽  
Vol 57 (3) ◽  
pp. 321-333 ◽  
Author(s):  
H. Moussa ◽  
S. EL-Gamal
Keyword(s):  
Pyruvate Carboxylase ◽  
Cadmium Toxicity ◽  
Triticum Aestivum L ◽  
Carboxylase Activity ◽  
Bisphosphate Carboxylase ◽  
Cd Accumulation ◽  
Phosphoenol Pyruvate ◽  
Relative Water ◽  
Aba Content

Treatment with CdCl 2 (0, 100, 400 and 1000 μM) resulted in the inhibition of root dry biomass and root elongation and to increased Cd accumulation in the roots. These treatments also decreased the relative water content, chlorophyll content, 14 CO fixation, phosphoenol pyruvate carboxylase and ribulose-1,5-bisphosphate carboxylase activity and abscisic acid (ABA) content, while increasing the malondialdehyde, hydrogen peroxide and free proline contents and causing changes in the chloroplast and root ultrastructure. Pretreatment of seeds with SA (500 μM) for 20 h resulted in the amelioration of these effects.

scholarly journals THE EFFECTS OF INDY ON FLY HEALTH

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S97-S98
Author(s):  
Blanka Rogina ◽  
Pooja Patel ◽  
Jacob Macro ◽  
Michael Li ◽  
Ryan Rogers
Keyword(s):  
Fat Body ◽  
Physiological Function ◽  
Krebs Cycle ◽  
Nutrient Sensing ◽  
Membrane Transporter ◽  
Beneficial Effects ◽  
Intestinal Integrity ◽  
Krebs Cycle Intermediates ◽  
Plasma Membrane Transporter

Abstract Indy (I’m not dead yet) gene encodes a plasma membrane transporter of Krebs’ cycle intermediates with highest affinity for citrate. Indy is the fly homolog of a mammalian mIndy (SLC13A5), which has the same physiological function. Reduced expression of the Indy gene extends longevity in fruit flies and worms. Genetic and pharmacological INDY reduction affects metabolism in flies, worms, mice, rats and non-human primates by affecting the levels of cytoplasmic citrate. In flies, INDY is predominantly expressed in the midgut, fat body and oenocytes, all tissues with a key role in metabolism. Our first goal was to examine our working hypothesis that INDY reduction in the midgut regulates citrate levels leading to metabolic changes that preserve intestinal stem cell (ISCs) homeostasis and slows aging by modifying Insulin/Insulin-like signaling (IIS). ISC homeostasis is vital for midgut homeostasis and contributes to health and longevity. We found that reduction of Indy preserves ISC homeostasis and intestinal integrity. The IIS is a key nutrient sensing pathway, which regulates growth, metabolism and longevity. Indy reduction is associated with decreased IIS activity. Our second goal was to examine the role of IIS in Indy mediated changes in ISC homeostasis and health. We found that at least some of INDY’s beneficial effects on fly health are mediated by the IIS.

FACTORS AFFECTING OXIDATION AND PHOSPHORYLATION BY SOYBEAN MITOCHONDRIA

1957 ◽  
Vol 35 (4) ◽  
pp. 515-525 ◽  
Author(s):  
Clayton M. Switzer ◽  
Frederick G. Smith
Keyword(s):  
Cytochrome C ◽  
Oxygen Uptake ◽  
Krebs Cycle ◽  
Maximum Activity ◽  
Differential Centrifugation ◽  
Factors Affecting ◽  
Soybean Seedlings ◽  
Active Particles ◽  
Exogenous Substrate ◽  
Krebs Cycle Intermediates

Active particles, presumed to be mitochondria, have been isolated by differential centrifugation from the hypocotyls of etiolated soybean seedlings. These particles were capable of oxidizing all Krebs cycle intermediates tested, although fumarate and oxaloacetate were oxidized relatively slowly. Oxygen uptake in the presence of succinate, pyruvate, or ketoglutarate was increased two to four times by the addition of ATP, MgSO4, and cytochrome c. Maximum activity was obtained when both sucrose and phosphate were added to the grinding and suspending media, and when the reaction mixture was buffered near pH 7.0. Endogenous oxidation was reduced 50% by one washing and at the same time the oxidation of exogenous substrate was increased two to three times. Average P:O ratios of 0.4, 0.8, and 0.9 were obtained without added hexokinase or fluoride for succinate, pyruvate, and ketoglutarate, respectively. These ratios were increased to 0.8, 1.2, and 1.5 by the addition of hexokinase. In all cases, 10−2 M NaF decreased oxygen uptake 30 to 40% without affecting P: O ratios. Isolated soybean particles appear to be similar in most respects to particles from other plants. Certain differences were found and are discussed.

scholarly journals The substrate specificity of acid α-glucosidase from rabbit muscle

1971 ◽  
Vol 124 (4) ◽  
pp. 701-711 ◽  
Author(s):  
T. N. Palmer
Keyword(s):  
Substrate Inhibition ◽  
Physiological Role ◽  
Liver Glycogen ◽  
Rabbit Muscle ◽  
Ph Optimum ◽  
Enzyme Action ◽  
Rate Limiting ◽  
Kinetics Of ◽  
Hydrolysis Of

1. Acid α-glucosidase was purified 3500-fold from rabbit muscle. 2. The enzyme was activated by cations, the degree of activation varying with the substrate. Enzyme action on glycogen was most strongly activated and activation was apparently of a non-competitive type. With rabbit liver glycogen as substrate, the relative Vmax. increased 15-fold, accompanied by an increase in Km from 8.3 to 68.6mm-chain end over the cation range 2–200mm-Na+ at pH4.5. Action on maltose was only moderately activated (1.3-fold, non-competitively) and action on maltotriose was marginally and competitively inhibited. 3. The pH optimum at 2mm-Na+ was 4.5 (maltose) and 5.1 (glycogen). Cation activation of enzyme action on glycogen was markedly pH-dependent. At 200mm-Na+, the pH optimum was 4.8 and activity was maximally stimulated in the range pH4.5–3.3. 4. Glucosidase action on maltosaccharides was associated with pronounced substrate inhibition at concentrations exceeding 5mm. Of the maltosaccharides tested, the enzyme showed a preference for p-nitrophenyl α-maltoside (Km 1.2mm) and maltotriose (Km 1.8mm). The extrapolated Km for enzyme action on maltose was 3.7mm. 5. The macromolecular polysaccharide substrate glycogen differed from linear maltosaccharide substrates in the kinetics of its interaction with the enzyme. Activity was markedly dependent on pH, cation concentration and polysaccharide structure. There was no substrate inhibition. 6. The enzyme exhibited constitutive α-1,6-glucanohydrolase activity. The Km for panose was 20mm. 7. The enzyme catalysed the total conversion of glycogen into glucose. The hydrolysis of α-1,6-linkages was apparently rate-limiting during the hydrolysis of glycogen. 8. Enzyme action on glycogen and maltose released the α-anomer of d-glucose. 9. The results are discussed in terms of the physiological role of acid α-glucosidase in lysosomal glycogen catabolism.

scholarly journals Production and Characterization of a Thermostable Alcohol Dehydrogenase That Belongs to the Aldo-Keto Reductase Superfamily

2006 ◽  
Vol 72 (1) ◽  
pp. 233-238 ◽  
Author(s):  
Ronnie Machielsen ◽  
Agustinus R. Uria ◽  
Servé W. M. Kengen ◽  
John van der Oost
Keyword(s):  
Alcohol Dehydrogenase ◽  
Pyrococcus Furiosus ◽  
Enantiomeric Excess ◽  
Physiological Role ◽  
Secondary Alcohols ◽  
Gene Encoding ◽  
Ph Optimum ◽  
Reduction Of Ketones

ABSTRACT The gene encoding a novel alcohol dehydrogenase that belongs to the aldo-keto reductase superfamily has been identified in the hyperthermophilic archaeon Pyrococcus furiosus. The gene, referred to as adhD, was functionally expressed in Escherichia coli and subsequently purified to homogeneity. The enzyme has a monomeric conformation with a molecular mass of 32 kDa. The catalytic activity of the enzyme increases up to 100°C, and a half-life value of 130 min at this temperature indicates its high thermostability. AdhD exhibits a broad substrate specificity with, in general, a preference for the reduction of ketones (pH optimum, 6.1) and the oxidation of secondary alcohols (pH optimum, 8.8). Maximal specific activities were detected with 2,3-butanediol (108.3 U/mg) and diacetyl-acetoin (22.5 U/mg) in the oxidative and reductive reactions, respectively. Gas chromatrography analysis indicated that AdhD produced mainly (S)-2-pentanol (enantiomeric excess, 89%) when 2-pentanone was used as substrate. The physiological role of AdhD is discussed.

Dark CO2 fixation by cell-free preparations of the wood of Robinia pseudoacacia

1974 ◽  
Vol 52 (4) ◽  
pp. 727-734 ◽  
Author(s):  
Wolfgang Höll
Keyword(s):  
Organic Compounds ◽  
Malic Enzyme ◽  
Co2 Fixation ◽  
Robinia Pseudoacacia ◽  
Physiological Role ◽  
Annual Rings ◽  
Ph Optimum ◽  
Robinia Pseudoacacia L ◽  
Dark Co2 Fixation

In the presence of phosphoenolpyruvate, cell-free preparations from distinct annual ring tissues of the trunk and the root of Robinia pseudoacacia L. incorporate 14CO2 into organic compounds. The CO2 fixation process exhibits a pH optimum at 7.8 and is activated by Mg2+. Aspartic acid contained 97% of the radioactivity incorporated. Oligosaccharides, malic acid, fumaric acid, glutamic acid, and three substances not identified with certainty show minor labeling. The activities of malate dehydrogenase (EC. 1.1.1.37), aspartate aminotransferase (EC. 2.6.1.1), and "malic enzyme" (EC. 1.1.1.40), involved in the further metabolism of the primary CO2 fixation product oxaloacetate, were detected spectrophotometrically in preparations from different annual rings of the trunk. Compared with the outer zones, the innermost part of the sapwood shows only little activity of these enzymes. The capacity to transfer CO2 into organic compounds decreases in the radial direction of both trunk and root wood. Heartwood preparations exhibit no CO2 fixation. In comparison to the trunk, the wood of the root shows only little dark CO2 fixation. The possible physiological role of this nonautotrophic CO2 binding in the wood of Robinia is discussed.

scholarly journals N-Cyclohexanecarbonylpentadecylamine: a selective inhibitor of the acid amidase hydrolysing N-acylethanolamines, as a tool to distinguish acid amidase from fatty acid amide hydrolase

2004 ◽  
Vol 379 (1) ◽  
pp. 99-106 ◽  
Author(s):  
Kazuhito TSUBOI ◽  
Christine HILLIGSMANN ◽  
Séverine VANDEVOORDE ◽  
Didier M. LAMBERT ◽  
Natsuo UEDA
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Amide Hydrolase ◽  
Acid Amide ◽  
Physiological Role ◽  
Ph Optimum ◽  
Ph Values ◽  
Amide Hydrolase ◽  
Derivatives Of ◽  
Fatty Acid Amide

Anandamide (N-arachidonoylethanolamine) and other bioactive N-acylethanolamines are degraded to their corresponding fatty acids and ethanolamine. This hydrolysis is mostly attributed to catalysis by FAAH (fatty acid amide hydrolase), which exhibits an alkaline pH optimum. In addition, we have identified another amidase which catalyses the same reaction exclusively at acidic pH values [Ueda, Yamanaka and Yamamoto (2001) J. Biol. Chem. 276, 35552–35557]. In attempts to find selective inhibitors of this acid amidase, we screened various derivatives of palmitic acid, 1-hexadecanol, and 1-pentadecylamine with N-palmitoylethanolamine as substrate. Here we show that N-cyclohexanecarbonylpentadecylamine inhibits the acid amidase from rat lung with an IC50 of 4.5 µM, without inhibiting FAAH at concentrations up to 100 µM. The inhibition was reversible and non-competitive. This compound also inhibited the acid amidase in intact alveolar macrophages. With the aid of this inhibitor, it was revealed that rat basophilic leukaemia cells possess the acid amidase as well as FAAH. Thus the inhibitor may be a useful tool to distinguish the acid amidase from FAAH in various tissues and cells and to elucidate the physiological role of the enzyme.

scholarly journals The Phosphoenolpyruvate Carboxykinase of Verticillium albo-atrum

Microbiology ◽  
2000 ◽  
Vol 81 (1) ◽  
pp. 21-26 ◽  
Author(s):  
R. E. Hartman ◽  
N. T. Keen
Keyword(s):  
Phosphoenolpyruvate Carboxykinase ◽  
Carbon Sources ◽  
Maximum Activity ◽  
Ph Optimum ◽  
Low Levels ◽  
Enzyme Functions ◽  
Increased Activity ◽  
Sodium And Potassium ◽  
Low Activity ◽  
Verticillium Albo Atrum

Partially purified phosphoenolpyruvate carboxykinase from Verticillium albo-atrum had a pH optimum of 6·2 and required manganese for maximum activity, having lesser activity with iron or cobalt. Sodium and potassium ions were slightly stimulatory. Adenosine-5′-diphosphate increased activity and inosine-5′-diphosphate supported low activity, but other nucleotides were ineffective. Inhibition of the enzyme by p-chloromercuribenzoate was partially reversed by dithiothreitol. Avidin had no effect on enzyme activity. Oxalacetate slightly stimulated the enzyme and NADP+ strongly inhibited, but aspartate and acetyl-CoA showed no effect. Low levels of phosphoenolpyruvate carboxykinase were present in cells grown on glucose, xylose, or glycerol. Aspartate, pyruvate, and acetate as carbon sources resulted in higher levels of activity and malate gave the highest. The data indicate that the enzyme functions physiologically in the gluconeogenic conversion of oxalacetate to phosphoenolpyruvate.

ENZYMES OF PYRUVATE AND PHOSPHOENOLPYRUVATE CARBOXYLATION IN RUMEN BACTERIA

1974 ◽  
Vol 54 (4) ◽  
pp. 595-603 ◽  
Author(s):  
A. S. ATWAL ◽  
F. D. SAUER
Keyword(s):  
Calcium Phosphate ◽  
Ammonium Sulphate ◽  
Pyruvate Carboxylase ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Rumen Fluid ◽  
Maximum Activity ◽  
Rumen Bacteria ◽  
Carboxylase Activity ◽  
Mixed Bacteria ◽  
Pep Carboxykinase

Extracts of mixed bacteria collected from bovine rumen fluid contained enzymes that carboxylated pyruvate and phosphoenolpyruvate (PEP). Fresh extracts showed high pyruvate carboxylase activity (EC 6.4.1.1. pyruvate carboxylase) which, however, was cold-labile and lost activity on dialysis at 4 C. Enzyme(s) catalyzing the carboxylation of PEP were stable under these conditions. The carboxylation of PEP was maximally stimulated by ADP and to a lesser degree by GDP. The ADP–requiring PEP carboxykinase [EC 4.1.1.49 phosphoenolpyruvate carboxykinase (ATP)] was equally active with either Mg++ or Mn++ and showed maximum activity at pH 6.5. The GDP–requiring PEP carboxykinase [EC 4.1.1.32 phosphoenolpyruvate carboxykinase (GTP)] required Mn++ and was almost inactive if Mg++ was substituted. Maximum activity was at pH 7.0. These nucleotides were most effective at 2.5-mM concentration and were inhibitory at higher concentrations. In the absence of added ADP or GDP, the carboxylation of PEP continued at a low but persistent rate. Precipitation with ammonium sulphate and adsorption on calcium phosphate gel resulted in fractions containing different proportions of the three activities. These results suggest that in mixed rumen bacterial extracts there are four separate enzymes capable of synthesizing oxaloacetate: one that catalyzes the carboxylation of pyruvate and three that catalyze the carboxylation of PEP.

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