PARTICIPATION OF THE GLYOXYLATE CYCLE IN THE METABOLISM OF ETHANOL BY CASTOR BEAN ENDOSPERM TISSUES

1966 ◽  
Vol 44 (4) ◽  
pp. 423-432 ◽  
Author(s):  
Carol A. Peterson ◽  
E. A. Cossins
Keyword(s):  
Castor Bean ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Experimental Period ◽  
Tricarboxylic Acid ◽  
Ethanol Metabolism ◽  
Short Term ◽  
Tissue Slices ◽  
Acidic Amino Acids ◽  
The Glyoxylate Cycle

The kinetics and pathway of ethanol metabolism in endosperm tissues of the germinating castor bean-have been studied by incubating tissue slices with micromolar quantities of ethanol-1-14C and ethanol-2-14C. In short term experiments, ethanol-14C was incorporated into the organic acids and acidic amino acids. When the experimental period was increased up to 1 hour, large amounts of ethanol-2-14C were incorporated into the sugars, and ethanol-1-14C was extensively incorporated into the respiratory carbon dioxide. Incorporation of ethanol-14C was stimulated by incubation of the tissues with glyoxylate. Ethanol metabolism was markedly inhibited by iodoacetate and malonate. These inhibitors also changed the distribution of14C in the products isolated. Isotopic competition studies indicated that ethanol was incorporated into the acids of the glyoxylate and the tricarboxylic acid cycles at rates substantially lower than acetate.The results are interpreted as being consistent with a metabolism of ethanol mainly via the glyoxylate cycle with some cycling of ethanol carbon through the tricarboxylic acid cycle.

THE TRICARBOXYLIC ACID AND GLYOXYLATE CYCLES IN XANTHOMONAS PHASEOLI (XP8)

1959 ◽  
Vol 5 (1) ◽  
pp. 1-8 ◽  
Author(s):  
N. B. Madsen ◽  
R. M. Hochster
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Sole Source ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
Main Pathway ◽  
The Individual ◽  
Acetate Medium ◽  
Terminal Oxidation ◽  
The Glyoxylate Cycle

Cell-free extracts of Xanthomonas phaseoli contain the individual enzymes of the tricarboxylic acid cycle, and it is suggested that this is the main pathway for the terminal oxidation of carbohydrate in this organism. X. phaseoli can grow on a medium containing acetate as the sole source of carbon. Cell-free extracts of such acetate-grown organisms contain the enzymes of the glyoxylate cycle, and it is concluded that the operation of this cycle permits the initial stages of synthesis of complex cell material from acetate at a rate sufficiently high to account for the observed rate of growth on the acetate medium. The two enzymes required to modify a tricarboxylic acid cycle into a glyoxylate cycle are present in very small amounts (malate synthetase) or absent entirely (isocitritase) in extracts of glucose-grown X. phaseoli.

scholarly journals Structure of glyoxysomal malate dehydrogenase (MDH3) from Saccharomyces cerevisiae

2018 ◽  
Vol 74 (10) ◽  
pp. 617-624 ◽  
Author(s):  
Shu Moriyama ◽  
Kazuya Nishio ◽  
Tsunehiro Mizushima
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Malate Dehydrogenase ◽  
Ternary Complex ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Tricarboxylic Acid ◽  
Mitochondrial Enzyme ◽  
Open Conformation ◽  
Metabolism Enzyme ◽  
The Glyoxylate Cycle

Malate dehydrogenase (MDH), a carbohydrate and energy metabolism enzyme in eukaryotes, catalyzes the interconversion of malate to oxaloacetate (OAA) in conjunction with that of nicotinamide adenine dinucleotide (NAD+) to NADH. Three isozymes of MDH have been reported in Saccharomyces cerevisiae: MDH1, MDH2 and MDH3. MDH1 is a mitochondrial enzyme and a member of the tricarboxylic acid cycle, whereas MDH2 is a cytosolic enzyme that functions in the glyoxylate cycle. MDH3 is a glyoxysomal enzyme that is involved in the reoxidation of NADH, which is produced during fatty-acid β-oxidation. The affinity of MDH3 for OAA is lower than those of MDH1 and MDH2. Here, the crystal structures of yeast apo MDH3, the MDH3–NAD+ complex and the MDH3–NAD+–OAA ternary complex were determined. The structure of the ternary complex suggests that the active-site loop is in the open conformation, differing from the closed conformations in mitochondrial and cytosolic malate dehydrogenases.

THE TRICARBOXYLIC ACID CYCLE, THE GLYOXYLATE CYCLE, AND THE ENZYMES OF GLUCOSE OXIDATION IN PSEUDOMONAS AERUGINOSA

1966 ◽  
Vol 12 (5) ◽  
pp. 1015-1022 ◽  
Author(s):  
Margaret von Tigerstrom ◽  
J. J. R. Campbell
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Glucose Oxidation ◽  
Nadh Oxidase ◽  
Specific Activity ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Succinic Dehydrogenase ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
The Glyoxylate Cycle

The enzymes of the glyoxylate cycle, the tricarboxylic acid cycle, glucose oxidation, and hydrogen transport were measured in extracts of Pseudomonas aeruginosa grown with glucose, α-ketoglutarate, or acetate as sole carbon source. The specific activity of isocitritase was increased 25-fold by growth on acetate whereas malate synthetase was increased only 4-fold. All of the enzymes of glucose metabolism, operative at the hexose level, were inducible. The enzymes of the tricarboxylic acid cycle were present under all conditions of growth but extracts from acetate-grown cells contained only one-quarter of the fumarase and pyruvic oxidase activity and half the malate-oxidizing activity of the other extracts. Transhydrogenase, NADH oxidase, and NADPH oxidase activities were similar in each type of extracts. Most of the enzymes were present in the soluble cytoplasm, exceptions being glucose oxidase, succinic dehydrogenase, and NADH oxidase.

scholarly journals The pathway of glycollate utilization in Chlorella pyrenoidosa

1970 ◽  
Vol 117 (5) ◽  
pp. 929-937 ◽  
Author(s):  
J. M. Lord ◽  
M. J. Merrett
Keyword(s):  
Soluble Fraction ◽  
Tricarboxylic Acid Cycle ◽  
Experimental Period ◽  
Chlorella Pyrenoidosa ◽  
Total Radioactivity ◽  
Tricarboxylic Acid ◽  
Short Term ◽  
Acid Cycle ◽  
Metabolic Sequence ◽  
Specific Activities

1. Exogenous glycollate was rapidly metabolized in both the light and the dark by photoautotrophically grown Chlorella pyrenoidosa. 2. The incorporation of 14C from [1-14C]glycollate by these cells was inhibited by the tricarboxylic acid-cycle inhibitors monofluoroacetate, diethylmalonate and arsenite, and also by α-hydroxypyrid-2-ylmethanesulphonate and isonicotinylhydrazine. 3. Short-term kinetic experiments showed over 80% of the total 14C present in the soluble fraction from the cells to be in glycine and serine after 10s. This percentage decreased with time whereas the percentage radioactivity in glycerate increased for up to 30s then remained steady. The percentage of the total radioactivity present in citrate increased over the experimental period. Malate was the only other tricarboxylic acid-cycle intermediate to become labelled. 4. The kinetic and inhibitor experiments supported the following pathway of glycollate incorporation: glycollate → glyoxylate → glycine → serine → hydroxypyruvate → glycerate → 3-phosphoglycerate → 2-phosphoglycerate → phosphoenolpyruvate → pyruvate → acetyl-CoA. 5. The specific activities of the enzymes catalysing this metabolic sequence in cell-free extracts were great enough to account for the observed rate of glycollate metabolism of 0.25μmol/h per mg dry wt. of cells in the light.

scholarly journals A Transcriptional Switch in the Expression of Yeast Tricarboxylic Acid Cycle Genes in Response to a Reduction or Loss of Respiratory Function

1999 ◽  
Vol 19 (10) ◽  
pp. 6720-6728 ◽  
Author(s):  
Zhengchang Liu ◽  
Ronald A. Butow
Keyword(s):  
Binding Site ◽  
Respiratory Function ◽  
Leucine Zipper ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Helix Loop Helix ◽  
Expression Of Genes ◽  
The Glyoxylate Cycle

ABSTRACT The Hap2,3,4,5p transcription complex is required for expression of many mitochondrial proteins that function in electron transport and the tricarboxylic acid (TCA) cycle. We show that as the cells’ respiratory function is reduced or eliminated, the expression of four TCA cycle genes, CIT1, ACO1, IDH1, andIDH2, switches from HAP control to control by three genes, RTG1, RTG2, and RTG3. The expression of four additional TCA cycle genes downstream ofIDH1 and IDH2 is independent of theRTG genes. We have previously shown that theRTG genes control the retrograde pathway, defined as a change in the expression of a subset of nuclear genes, e.g., the glyoxylate cycle CIT2 gene, in response to changes in the functional state of mitochondria. We show that thecis-acting sequence controlling RTG-dependent expression of CIT1 includes an R box element, GTCAC, located 70 bp upstream of the Hap2,3,4,5p binding site in theCIT1 upstream activation sequence. The R box is a binding site for Rtg1p-Rtg3p, a heterodimeric, basic helix-loop-helix/leucine zipper transcription factor complex. We propose that in cells with compromised mitochondrial function, the RTG genes take control of the expression of genes leading to the synthesis of α-ketoglutarate to ensure that sufficient glutamate is available for biosynthetic processes and that increased flux of the glyoxylate cycle, via elevated CIT2 expression, provides a supply of metabolites entering the TCA cycle sufficient to support anabolic pathways. Glutamate is a potent repressor of RTG-dependent expression of genes encoding both mitochondrial and nonmitochondrial proteins, suggesting that it is a specific feedback regulator of the RTG system.

scholarly journals The localization of enzymes of intermediary metabolism in Astasia and Euglena

1973 ◽  
Vol 134 (2) ◽  
pp. 607-616 ◽  
Author(s):  
Nicole Bégin-Heick
Keyword(s):  
Succinate Dehydrogenase ◽  
Isocitrate Lyase ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Intracellular Localization ◽  
Tricarboxylic Acid ◽  
Malate Synthase ◽  
Particulate Fraction ◽  
Acid Cycle ◽  
The Glyoxylate Cycle

Results are presented on the intracellular localization of some of the enzymes of gluconeogenesis, of the tricarboxylic acid cycle and of related enzymes in Astasia and Euglena grown with various substrates. The results indicate the particulate nature of at least part of the malate synthase of Astasia and of part of the malate synthase and isocitrate lyase in Euglena. However, the presence of glyoxysomes (microbodies) in Astasia and Euglena is still open to question, since it has not, so far, been possible to separate the enzymes of the glyoxylate cycle from succinate dehydrogenase in the particulate fraction.

A MATHEMATICAL ANALYSIS OF THE COMBINED TRICARBOXYLIC ACID - GLYOXYLATE CYCLES

1967 ◽  
Vol 45 (6) ◽  
pp. 863-872
Author(s):  
R. M. R. Branion ◽  
B. F. J. Caddick ◽  
W. B. McConnell
Keyword(s):  
Experimental Data ◽  
Mathematical Analysis ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
Combined Operation ◽  
Simplifying Assumptions ◽  
The Individual ◽  
The Glyoxylate Cycle

The problem of interpreting data on the distribution of isotopic carbon in intermediates of the tricarboxylic acid cycle and the glyoxylate cycle is discussed. An effort is made to examine mathematically the effects of cycling on the distribution of isotope in the carbon skeletons of intermediates of these cycles. Consideration is given to the individual cycles and to combinations of the two. Because the systems are highly complex, a number of simplifying assumptions are made which limit the usefulness of the equations derived for dealing with experimental data. However, some significant features of labelling that result from combined operation of the two cycles are emphasized, which should make it possible to estimate their relative contributions more reliably than by qualitative inspection of the data.

scholarly journals Studies of intermediary metabolism in germinating pea cotyledons. The pathway of ethanol metabolism and the role of the tricarboxylic acid cycle

1967 ◽  
Vol 105 (1) ◽  
pp. 323-331 ◽  
Author(s):  
D. S. Cameron ◽  
E. A. Cossins
Keyword(s):  
Carbon Dioxide ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Ethanol Metabolism ◽  
Similar Data ◽  
Tissue Slices ◽  
Acid Cycle ◽  
Pea Seedlings ◽  
Fixation Of Carbon Dioxide

1. The pathway of ethanol metabolism in cotyledons of 3-day-old pea seedlings has been examined by incubating tissue slices with [1−14C]ethanol and [2−14C]ethanol for periods up to 1hr. 2. Ethanol was rapidly incorporated into citrate and glutamate but relatively small amounts of 14C were present in the evolved carbon dioxide even after 1hr. of ethanol metabolism. 3. Similar data were obtained from experiments in which [1,2−14C2]acetaldehyde and [14C]acetate were supplied. 4. The results are interpreted as indicating that ethanol is metabolized essentially via the reactions of the tricarboxylic acid cycle with a substantial drain of α-oxoglutarate to support the biosynthesis of glutamate. 5. It is concluded that oxaloacetate, required for the incorporation of ethanol into citrate, arises mainly from the transamination of aspartate and the fixation of carbon dioxide.

PATHWAYS FOR THE METABOLISM OF GLYOXYLATE AND ACETATE IN GERMINATING FATTY SEEDS

1965 ◽  
Vol 43 (9) ◽  
pp. 1531-1541 ◽  
Author(s):  
S. K. Sinha ◽  
E. A. Cossins
Keyword(s):  
Amino Acids ◽  
Castor Bean ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Amino Acid Biosynthesis ◽  
Acid Oxidation ◽  
Acid Biosynthesis ◽  
Tissue Slices ◽  
Acid Cycle ◽  
Pumpkin Seeds

Cotyledons of germinating sunflower, pumpkin, linseed, and watermelon seeds and the endosperm of germinating castor bean seeds have been examined for their ability to utilize glyoxylate-C14and acetate-C14for the biosynthesis of amino acids. All of the tissues examined readily utilized these acids when supplied in micromolar amounts to tissue slices. The chief products of this utilization included the organic acids of the glyoxylate and tricarboxylic acid cycles and a number of amino acids and amides. The results are interpreted as indicating that, in sunflower, watermelon, linseed, and pumpkin seeds, malate formed in the malate synthetase reaction is metabolized by the partial reactions of the tricarboxylic acid cycle. α-Ketoglutarate produced by these reactions is extensively utilized in the biosynthesis of glutamate, γ-aminobutyrate, and glutamine. In agreement with data already published, castor bean endosperm utilized acetate for the biosynthesis of sugars. This tissue also utilized glyoxylate for the formation of glycine, serine, glycollate, and malate. It is concluded that, with the exception of castor bean endosperm, acetyl CoA arising as a result of fatty acid oxidation might be utilized for amino acid biosynthesis via the partial reactions of the glyoxylate and tricarboxylic acid cycles.

Changes in activity of certain enzymes of the tricarboxylic acid cycle and the glyoxylate cycle during the initiation of conidiation of Aspergillus niger

1969 ◽  
Vol 15 (10) ◽  
pp. 1207-1212 ◽  
Author(s):  
J. C. Galbraith ◽  
J. E. Smith
Keyword(s):  
Life Cycle ◽  
Aspergillus Niger ◽  
Isocitrate Lyase ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
Glycine Synthesis ◽  
The Glyoxylate Cycle

The activities of certain enzymes of the tricarboxylic acid (TCA) cycle and the glyoxylate cycle (GLC) varied during growth of Aspergillus niger as a function of the stage of the life cycle and of the growth medium. Isocitrate dehydrogenase (carboxylating) and isocitrate lyase each showed a marked increase in activity prior to sporulation. There were no similar increases in vegetative cultures. It is proposed that isocitrate lyase is functional in glycine synthesis and that a source of glyoxylate may be indispensable to the expression of sporulation.

Sign in / Sign up

Export Citation Format

Share Document