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.

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.

scholarly journals Effect of thyroid hormone on metabolic compartmentation in the developing rat brain

1971 ◽  
Vol 121 (3) ◽  
pp. 469-481 ◽  
Author(s):  
A. J. Patel ◽  
R. Balázs
Keyword(s):  
Amino Acids ◽  
Thyroid Hormone ◽  
Tricarboxylic Acid Cycle ◽  
Specific Radioactivity ◽  
Tricarboxylic Acid ◽  
The Other ◽  
Developmental Changes ◽  
Acid Cycle ◽  
Metabolic Compartmentation ◽  
Age Dependent

1. The effects of treatment with thyroid hormone (tri-iodothyronine) and of neonatal thyroidectomy on the cerebral metabolism of [U-14C]leucine were investigated during the period of functional maturation of the rat brain extending from 9 to 25 days after birth. 2. Age-dependent changes in the labelling of brain constituents under normal conditions appear to depend on changes in the availability of blood-borne [14C]leucine resulting from differential rates of growth of body and brain; but developmental changes in the pool size of free leucine and in the rates of protein synthesis and oxidation of leucine are also involved. 3. Treatment with thyroid hormone had no significant effect on the conversion of leucine carbon into proteins and lipids; and the age-dependent changes in the concentration and specific radioactivity of leucine were similar to controls. On the other hand there was an acceleration in the conversion of leucine carbon into amino acids associated with the tricarboxylic acid cycle. These observations indicate that leucine oxidation was the process mainly affected. 4. The specific radioactivity of glutamine relative to that of glutamate was used as an index of metabolic compartmentation in brain tissue. Treatment with thyroid hormone advanced the development of metabolic compartmentation. 5. Neonatal thyroidectomy led to a marked decrease in the conversion of leucine carbon into proteins and lipids and to a significant increase in the amount of 14C combined in the amino acids associated with the tricarboxylic acid cycle. The age-dependent increase in the glutamate/glutamine specific-radioactivity ratio was strongly retarded. 6. The increased conversion of leucine carbon into cerebral amino acids applied to glutamate and aspartate, but not to glutamine and γ-aminobutyrate. This observation facilitated the understanding of the effects of thyroid deprivation on brain metabolism and provided new evidence for the allocation of morphological structures to the metabolic compartments in brain tissue. 7. In contrast with the marked effects of the thyroid state on metabolic compartmentation, it had relatively little effect on the developmental changes in the concentration of amino acids in the brain. 8. The rate of conversion of leucine carbon into the ‘cycle amino acids’ both under normal conditions and in thyroid deficiency indicated a special metabolic relationship between glutamate and aspartate on the one hand, and glutamine and γ-aminobutyrate on the other.

Effect of process parameters on succinic acid production in Escherichia coli W3110 and enzymes involved in the reductive tricarboxylic acid cycle

2006 ◽  
Vol 52 (9) ◽  
pp. 893-902 ◽  
Author(s):  
Jasmine Isar ◽  
Lata Agarwal ◽  
Saurabh Saran ◽  
Pritesh Gupta ◽  
Rajendra Kumar Saxena
Keyword(s):  
Escherichia Coli ◽  
Succinic Acid ◽  
Process Optimization ◽  
Enzyme Activities ◽  
Acid Production ◽  
Tricarboxylic Acid Cycle ◽  
Sucrose Concentration ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
Succinic Acid Production

The effect of process optimization on succinic acid production by Escherichia coli W3110 and on enzymes involved in the reverse tricarboxylic acid cycle was studied. Approximately, 7.02 g L–1 of succinic acid was produced in 60 h at pH 7.0 in 500 mL anaerobic bottles containing 300 mL of the medium, wherein the sucrose concentration was 2.5%, the ratio of tryptone to ammonium hydrogen phosphate was 1:1, and the concentration of magnesium carbon ate was 1.5%. When these optimized fermentation conditions were employed in a 10 L bioreactor, 11.2 g L–1 of succinic acid was produced in 48 h. This is a 10-fold increase in succinic acid production from the initial titer of 0.94 g L–1. This clearly indicates the importance of process optimization, where by manipulating the media composition and production conditions, a remarkable increase in the production of the desired biomolecule can be obtained. The production of succinic acid is a multi-step reaction through the reverse tricarboxylic acid cycle. A linear relationship was observed between succinic acid production and the enzyme activities. The enzyme activities were found to increase in the order phospho-enol-pyruvate carboxylase < malate dehydrogenase < fumarase < fumarate reductase. The activity of phospho-enol-pyruvate carboxykinase was also estimated. Results indicate that this enzyme was not a very active participant in the production of succinic acid, since it catalyzes the phosphorylation of oxaloacetic acid to yield phospho-enol-pyruvate.Key words: anaerobic production, succinic acid, Escherichia coli, process optimization, reverse tricarboxylic acid cycle enzymes, fermentation.

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