scholarly journals Identification of an NAD(P)+-dependent ‘malic’ enzyme in small-intestinal-mucosal mitochondria

1979 ◽  
Vol 184 (1) ◽  
pp. 185-188 ◽  
Author(s):  
L A Sauer ◽  
R T Dauchy ◽  
W O Nagel
Keyword(s):  
Intestinal Mucosa ◽  
Malic Enzyme ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Kinetic Properties ◽  
Small Intestinal Mucosa ◽  
Intracellular Location ◽  
Acid Cycle ◽  
Small Intestinal ◽  
Tricarboxylic Acid Cycle Intermediates

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.

scholarly journals Role of NADP+-linked malic enzymes as regulators of the pool size of tricarboxylic acid-cycle intermediates in the perfused rat heart

1987 ◽  
Vol 243 (3) ◽  
pp. 853-857 ◽  
Author(s):  
K E Sundqvist ◽  
J Heikkilä ◽  
I E Hassinen ◽  
J K Hiltunen
Keyword(s):  
Malic Enzyme ◽  
Rat Heart ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Mass Action ◽  
Acid Cycle ◽  
Perfused Rat Heart ◽  
Order Of Magnitude ◽  
Propionate Oxidation ◽  
Tricarboxylic Acid Cycle Intermediates

Cytosolic and mitochondrial concentrations of malate, 2-oxoglutarate, isocitrate and pyruvate in the isolated perfused rat heart were measured by non-aqueous tissue fractionation, taking the NADP-linked isocitrate dehydrogenase as indicator reactions for the free [NADPH]/[NADP+] ratios. The mass-action ratios of NADP-linked malic enzymes (EC 1.1.1.40) were found to be on the side of pyruvate carboxylation by more than one order of magnitude in both the cytosolic and the mitochondrial spaces in hearts perfused with glucose, whereas during propionate perfusion this ratio approached the equilibrium constant (Keq.) of malic enzyme. The results consequently indicate that the NADP-linked malic enzymes cannot be responsible for the feed-out (cataplerotic) reactions from the tricarboxylic acid cycle which occur during glucose perfusion. Only when other anaplerotic fluxes into the cycle are high, as during propionate oxidation, which results in accumulation of tricarboxylic acid-cycle intermediates, is a steady state reached which allows efflux via the malic enzyme.

scholarly journals Triheptanoin partially restores levels of tricarboxylic acid cycle intermediates in the mouse pilocarpine model of epilepsy

2013 ◽  
Vol 129 (1) ◽  
pp. 107-119 ◽  
Author(s):  
Mussie G. Hadera ◽  
Olav B. Smeland ◽  
Tanya S. McDonald ◽  
Kah Ni Tan ◽  
Ursula Sonnewald ◽  
...  
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
Pilocarpine Model ◽  
Tricarboxylic Acid Cycle Intermediates

scholarly journals Metabolic phases during the development of granulation tissue

1967 ◽  
Vol 105 (1) ◽  
pp. 333-341 ◽  
Author(s):  
Kirsti Lampiaho ◽  
E. Kulonen
Keyword(s):  
Granulation Tissue ◽  
Collagen Synthesis ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Acid Cycle ◽  
Short Period ◽  
Tricarboxylic Acid Cycle Intermediates ◽  
Observation Period

1. The metabolism of incubated slices of sponge-induced granulation tissue, harvested 4–90 days after the implantation, was studied with special reference to the capacity of collagen synthesis and to the energy metabolism. Data are also given on the nucleic acid contents during the observation period. Three metabolic phases were evident. 2. The viability of the slices for the synthesis of collagen was studied in various conditions. Freezing and homogenization destroyed the capacity of the tissue to incorporate proline into collagen. 3. Consumption of oxygen reached the maximum at 30–40 days. There was evidence that the pentose phosphate cycle was important, especially during the phases of the proliferation and the involution. The formation of lactic acid was maximal at about 20 days. 4. The capacity to incorporate proline into collagen hydroxyproline in vitro was limited to a relatively short period at 10–30 days. 5. The synthesis of collagen was dependent on the supply of oxygen and glucose, which latter could be replaced in the incubation medium by other monosaccharides but not by the metabolites of glucose or tricarboxylic acid-cycle intermediates.

The Ethylmalonyl-CoA Pathway for Methane-based Biorefineries: A Case Study of Using Methylosinus trichosporium OB3b, an Alpha-proteobacterial Methanotroph, for Producing 2-Hydroxyisobutyric Acid and 1,3-Butanediol from Methane

2021 ◽  
Author(s):  
Dung Hoang Anh Mai ◽  
Thu Thi Nguyen ◽  
Eun Yeol Lee
Keyword(s):  
Carbon Metabolism ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Methylosinus Trichosporium Ob3b ◽  
Methylosinus Trichosporium ◽  
Acid Cycle ◽  
Hydroxyisobutyric Acid ◽  
Tricarboxylic Acid Cycle Intermediates ◽  
Alpha Proteobacteria

The ethylmalonyl-CoA pathway is one of three known anaplerotic pathways that replenish tricarboxylic acid cycle intermediates and plays a major role in the carbon metabolism of many alpha-proteobacteria including Methylosinus...

13C isotopomer model for estimation of anaplerotic substrate oxidation via acetyl-CoA

1996 ◽  
Vol 271 (4) ◽  
pp. E788-E799 ◽  
Author(s):  
F. M. Jeffrey ◽  
C. J. Storey ◽  
A. D. Sherry ◽  
C. R. Malloy
Keyword(s):  
Biochemical Analysis ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acetyl Coa ◽  
Acid Cycle ◽  
Propionate Metabolism ◽  
13C Nuclear Magnetic Resonance ◽  
Isotopomer Analysis ◽  
Tricarboxylic Acid Cycle Intermediates ◽  
Anaplerotic Pathway

A previous model using 13C nuclear magnetic resonance isotopomer analysis provided for direct measurement of the oxidation of 13C-enriched substrates in the tricarboxylic acid cycle and/or their entry via anaplerotic pathways. This model did not allow for recycling of labeled metabolites from tricarboxylic acid cycle intermediates into the acetyl-CoA pool. An extension of this model is now presented that incorporates carbon flow from oxaloacetate or malate to acetyl-CoA. This model was examined using propionate metabolism in the heart, in which previous observations indicated that all of the propionate consumed was oxidized to CO2 and water. Application of the new isotopomer model shows that 2 mM [3-13C]propionate entered the tricarboxylic acid cycle as succinyl-CoA (an anaplerotic pathway) at a rate equal to 52% of tricarboxylic acid cycle turnover and that all of this carbon entered the acetyl-CoA pool and was oxidized. This was verified using standard biochemical analysis; from the rate (mumol.min-1.g dry wt-1) of propionate uptake (4.0 +/- 0.7), the estimated oxygen consumption (24.8 +/- 5) matched that experimentally determined (24.4 +/- 3).

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