A COMPARISON OF THE OXIDATIVE METABOLISM OF LIGHT AND DARK GROWN RHODOSPIRILLUM RUBRUM

1956 ◽  
Vol 2 (4) ◽  
pp. 427-432 ◽  
Author(s):  
P. G. Crook ◽  
E. S. Lindstrom
Keyword(s):  
Oxidative Metabolism ◽  
Rhodospirillum Rubrum ◽  
Tricarboxylic Acid Cycle ◽  
Rhodopseudomonas Palustris ◽  
Succinic Dehydrogenase ◽  
Tricarboxylic Acid ◽  
The Other ◽  
Acid Cycle ◽  
Keto Acids ◽  
Soluble Enzymes

Using a manometric or a dehydrogenase assay, activity for most of the intermediates of the tricarboxylic acid cycle was demonstrated in extracts from Rhodo spirillum rubrum grown photosynthetically (anaerobic light), heterotrophically (aerobic dark), or a combination of both (aerobic light). Dehydrogenases for succinate and α-ketoglutarate were more active in extracts from cells grown photosynthetically. Extracts from cells grown heterotrophically had the greatest oxidative activity. Succinic dehydrogenase was associated with larger macromolecular units in all extracts while the other dehydrogenases behaved as soluble enzymes. Conditions of cultivation affected the rate at which keto acids were formed from citrate. Rhodopseudomonas palustris also possessed tricarboxylic acid dehydrogenases whether grown photosynthetically or heterotrophically.

THE ENZYMES OF THE TRICARBOXYLIC ACID CYCLE OF PSEUDOMONAS AERUGINOSA

1956 ◽  
Vol 2 (4) ◽  
pp. 433-440 ◽  
Author(s):  
Jack J. R. Campbell ◽  
Roberts A. Smith
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Malic Acid ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
The Other ◽  
Acid Cycle ◽  
High Ph ◽  
Optimum Activity ◽  
Fresh Cell ◽  
Cell Extracts

It was demonstrated that Pseudomonas aeruginosa possesses all the enzymes necessary for the oxidation of pyruvate to CO2 and water without passing through the conventional intermediates oxalosuccinate and α-ketoglutarate. These intermediates are bypassed by the action of the enzyme isocitratase which splits d-isocitrate to succinate plus glyoxylate. This reaction was shown to be readily reversible. The malic acid dehydrogenase content was low and in addition this enzyme required a high pH for optimum activity. In fresh cell extracts at pH 7.4 its activity was only 10% that of the other enzymes of the cycle. The malic and isocitric dehydrogenases were TPN specific. The organism was also shown to possess all the enzymes necessary for the operation of the conventional tricarboxylic acid cycle.

THE METABOLISM OF PUTRESCINE (1,4-DIAMINOBUTANE) BY MYCOBACTERIA ISOLATED FROM FISH: II. STUDIES WITH ARSENITE-INHIBITED CELLS AND CELL-FREE EXTRACTS

1967 ◽  
Vol 13 (5) ◽  
pp. 521-531 ◽  
Author(s):  
T. P. T. Evelyn
Keyword(s):  
Succinic Acid ◽  
Tricarboxylic Acid Cycle ◽  
Significant Proportion ◽  
Tricarboxylic Acid ◽  
The Other ◽  
Aminobutyric Acid ◽  
Succinic Semialdehyde ◽  
Amino Group ◽  
Intact Cells ◽  
Acid Cycle

Three mycobacterial strains isolated from fish degraded putrescine by a pathway in which γ-aminobutyraldehyde (Δ′-pyrroline), γ-aminobutyric acid, succinic semialdehyde, and succinic acid were intermediates. These results agree substantially with those of other workers using different microorganisms. Intact cells utilized γ-aminobutyric acid in a transaminase reaction with endogenously supplied α-ketoglutarate to produce succinic semialdehyde and glutamate. Studies with arsenite-poisoned cells showed that a significant proportion of putrescine was metabolized via pyruvate and alanine. When putrescine-1,4-14C was substrate, HCl extracts of cells contained radioactive aspartate and glutamate in addition to alanine. The further metabolism of succinate therefore proceeded in two directions: one yielding oxalacetate and α-ketoglutarate by way of the tricarboxylic acid cycle, and the other branching off the cycle to yield pyruvate. Studies with cell-free extracts suggested that putrescine nitrogen was assimilated via glutamate, which served as the amino-group donor to yield alanine and aspartate.

Modulation of glucose metabolism in macrophages by products of nitric oxide synthase

1993 ◽  
Vol 264 (6) ◽  
pp. C1594-C1599 ◽  
Author(s):  
J. E. Albina ◽  
B. Mastrofrancesco
Keyword(s):  
Nitric Oxide ◽  
Glucose Metabolism ◽  
Oxidative Metabolism ◽  
Culture Media ◽  
Tricarboxylic Acid Cycle ◽  
Specific Inhibitor ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
The Impact ◽  
By Products

Nitric oxide (NO) is a product of L-arginine metabolism that suppresses cellular oxidative metabolism through the inhibition of tricarboxylic acid cycle and electron transport chain enzymes. The impact of NO synthase (NOS) activity on specific pathways of glucose metabolism in freshly harvested and overnight-cultured rat resident peritoneal macrophages, at rest and after stimulation with zymosan, was investigated using radiolabeled glucose. NOS activity was modulated through the L-arginine concentration in culture media and the use of its specific inhibitor, NG-monomethyl-L-arginine, and quantitated using radiolabeled L-arginine. Results demonstrated that NOS activity was associated with increased glucose disappearance, glycolysis, and hexose monophosphate shunt activity and, in line with the known inhibition of oxidative metabolism associated with the production of NO, with a decrease in the flux of glucose and butyrate carbon through the tricarboxylic acid cycle. In addition, the relative increase in glucose utilization that follows zymosan stimulation was enhanced by treatments that suppressed NOS activity. These results demonstrate that the characteristics of glucose metabolism by macrophages are, to a significant extent, determined by products of NOS.

scholarly journals IN VITRO EFFECTS OF FLUORIDE ON TRICARBOXYLIC ACID CYCLE DEHYDROGENASES AND OXIDATIVE PHOSPHORYLATION: PART I

1967 ◽  
Vol 15 (4) ◽  
pp. 195-201 ◽  
Author(s):  
C. JAMES LOVELACE ◽  
GENE W. MILLER
Keyword(s):  
Oxidative Phosphorylation ◽  
Competitive Inhibition ◽  
Tricarboxylic Acid Cycle ◽  
Succinic Dehydrogenase ◽  
Tricarboxylic Acid ◽  
Initial Increase ◽  
Acid Cycle ◽  
Oxidase System ◽  
Vitro Effect

Studies were conducted on the in vitro effect of fluoride on the succinic oxidase system utilizing mitochondria obtained from cauliflower. Preincubation of mitochondria with fluoride did not increase inhibition of succinic oxidase. Various other tricarboxylic acid cycle substrates were used to determine their sensitivity to fluoride; only succinate oxidation was affected. A series of succinate concentrations in the presence and in the absence of fluoride showed increased activity of succinic dehydrogenase, which indicated competitive inhibition. Various concentrations of phosphate in the absence of fluoride showed that phosphate had only slight effects on the succinic 2,6-dichlorophenolindophenol reductase component of the succinic oxidase system. In the absence of phosphate, various concentrations of fluoride showed an initial increase in activity followed by a decrease in activity of succinic 2,6-dichlorophenolindophenol reductase. In the presence of phosphate, fluoride caused marked inhibition of succinic 2,6-dichlorophenolindophenol reductase. It is believed that this inhibition results from an enzyme-fluorophosphate complex which has a lower dissociation constant than that of the enzyme-substrate complex. An oxidative phosphorylation study indicated that both respiration and phosphorylation were inhibited.

scholarly journals Studies on the Metabolism of Locust Fat Body

1959 ◽  
Vol 36 (4) ◽  
pp. 665-675
Author(s):  
A. N. CLEMENTS
Keyword(s):  
Amino Acids ◽  
Sodium Acetate ◽  
Flight Muscle ◽  
Fat Body ◽  
Enzyme System ◽  
Tricarboxylic Acid Cycle ◽  
Succinic Dehydrogenase ◽  
Tricarboxylic Acid ◽  
Acid Cycle

1. The incorporation of glycine-14C (G), leucine-14C (G), sodium acetate-2-14C and glucose-14C (G) into Schistocerca fat body was studied under in vitro conditions, and the distribution of radioactivity in the various fat body fractions and the labelling of compounds within the fractions is described. 2. The overall picture was of high incorporation into fat and protein and of very low incorporation into glycogen. 3. Incubation with glycine-14C led to radioactivity appearing in the glycine and serine of the protein and of the amino acid pool. Incubation with sodium acetate-2-14C led to radioactivity appearing in glutamate, proline, aspartate and alanine, showing that the intermediates of the tricarboxylic acid cycle provide the carbon skeletons of certain amino acids. Glucose-14C was largely converted to trehalose. 4. Succinic dehydrogenase and the condensing enzyme system were shown to be present in fat body, contrary to previous reports. The succinic oxidase system was highly labile on homogenizing the tissue. 5. Fat body, unlike flight muscle, used glycine-14C and leucine-14C as respiratory substrates, and it is suggested that fat body acts like the vertebrate liver by transdeaminating amino acids and making them available for further metabolism by other tissues.

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.

STUDIES OF THE KETO ACIDS OF WHEAT: I. BEHAVIOR DURING GROWTH

1958 ◽  
Vol 36 (1) ◽  
pp. 165-177 ◽  
Author(s):  
R. M. Krupka ◽  
G. H. N. Towers
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Nitrogen Atmosphere ◽  
Keto Acid ◽  
Acid Cycle ◽  
Oxaloacetic Acid ◽  
Early Stages ◽  
Etiolated Seedlings ◽  
Keto Acids

A survey of the keto acids of wheat showed α-ketoglutaric, pyruvic, glyoxylic, hydroxypyruvic, α-ketoisocaproic, oxaloacetic, and a number of unidentified keto acids to be present. The behavior of α-ketoglutarate, pyruvate, and glyoxylate in germinating seedlings under different conditions in light and dark and in aging leaves and in starving excised leaves was studied. These keto acids appeared and reached a peak during the early stages of germination. Oxaloacetic acid was present only in trace amounts. An unidentified keto acid was found to accumulate in etiolated seedlings. The effect of a nitrogen atmosphere on keto acid levels and the incorporation of glucose-C14into pyruvate, α-ketoglutarate, and oxaloacetate provided evidence for the operation of the tricarboxylic acid cycle in seedlings.

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