The tricarboxylic acid pathway in Desulfovibrio

1977 ◽  
Vol 23 (7) ◽  
pp. 916-921 ◽  
Author(s):  
A. J. Lewis ◽  
J. D. A. Miller

Strains of two species of Desulfovibrio were examined for enzymes of the tricarboxylic acid cycle and related pathways. Pyruvate carboxylase (EC 6.4.1.1) is present, and α-ketoglutarate is formed via the tricarboxylic acids. Glutamate, but not succinyl-CoA, arises from α-ketoglutarate. A pathway exists from pyruvate by malic enzyme (EC 1.1.1.39) activity to malate, then fumarate and succinate, again with no evidence of succinyl-CoA formation. The enzymes concerned with metabolism of these dicarboxylic acids show greater activity in the strains that can grow by fumarate dismutation. Glutamate (or glutamine), α-ketoglutarate, and yeast extract repress the enzymes that metabolize the tricarboxylic acids. There appears to be no glyoxylate cycle in Desulfovibrio vulgaris or D. desulfuricans.

1959 ◽  
Vol 5 (1) ◽  
pp. 1-8 ◽  
Author(s):  
N. B. Madsen ◽  
R. M. Hochster

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.


Author(s):  
K. S. Ostrenko ◽  
V. P. Galochkina ◽  
V. О. Lemiasheuski ◽  
A. V. Agafonova ◽  
A. N. Ovcharova ◽  
...  

The paper is the fundamental beginning of research series aimed at understanding the processes associated with high performance in higher animals. The research aim is to study correlation of dicarboxylic acid cycle with tricarboxylic acid cycle with establishment of activity and dislocation of enzymes, confirming the hypothesis of availability and active metabolic participation of peroxisome in highly productive animals. Research was conducted on the basis of the VNIIFBiP animal vivarium in 2019 with a group of piglets of the Irish Landrace breed (n = 10). After slaughter at the age of 210 days, the nuclear (with large tissue particles), mitochondrial and postmitochondrial fractions of the liver were studied with assessment of succinate dehydrogenase and activity of other dehydrogenes of the Krebs cycle. It was found that peroxisomes act as universal agents of communication and cooperation, and microtelets are able to generate various chemical signals that carry information, to control and arrange a number of mechanisms in the metabolic processes in the body. Despite the fact that the Krebs cycle dehydrogenases are considered mitochondrial enzymes, the experiment showed an increase in activity of priruvate dehydrogenase (P > 0.1), isocitrate dehydrogenase (0.1 > P > 0.05) and malate dehydrogenase (0.1 > P > 0.05), which, when comparing the mitochondrial and postmitochondrial fractions, indicates a higher activity of peroxisomal fractions. The peroxisome localization place is the postmitochondrial fraction, and the lower layer contains larger peroxisomes to a greater extent, while the upper layer contains smaller ones. It was found that indicator enzymes of glyoxylate cycle isocitratliase and malate synthase exhibit catalytic activity in the peroxisomal fraction of liver of highly productive pigs. The obtained data on functioning of key glyoxylate cycle enzymes and their intracellular compartmentalization in highly productive pigs allow learning more about the specifics of metabolism and its regulation processes. Application of this knowledge in practice opens up prospects for rationalizing the production of livestock products of increased quantity, improved quality with less feed, labor and financial resources spent.


1966 ◽  
Vol 12 (5) ◽  
pp. 1015-1022 ◽  
Author(s):  
Margaret von Tigerstrom ◽  
J. J. R. Campbell

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.


1979 ◽  
Vol 184 (1) ◽  
pp. 185-188 ◽  
Author(s):  
L A Sauer ◽  
R T Dauchy ◽  
W O Nagel

An NAD(P)+-dependent ‘malic’ enzyme is shown to be present in mitochondria from small-intestinal mucosa. The intracellular location, activity and regulatory kinetic properties of the enzyme suggest that it participates in the major energy-producing pathway for net oxidation of glutamine-derived tricarboxylic acid-cycle intermediates.


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