The aerobic utilization of pyruvate in plant tissues

1959 ◽  
Vol 150 (939) ◽  
pp. 192-198 ◽  
Keyword(s):  
Amino Acids ◽  
Specific Activity ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Methyl Groups ◽  
Plant Tissues ◽  
Root Tips ◽  
Acid Cycle ◽  
Amino Butyric Acid ◽  
Apple Tissue

Pyruvate with 14 C-labelling in the carbonyl and methyl groups was supplied to apple tissue and to root tips of barley. After incubation the labelling was found in a series of carboxylic acids and in alanine, glutamic acid, aspartic acid and γ -amino-butyric acid. Glutamine and asparagine were also labelled; but several other amino acids whose presence was demonstrated were without label after 4 h. Sugars and polysaccharides were also unlabelled. The CO 2 given off invariably contained 14 C, but the specific activity was much lower than that of the pyruvate supplied. It is concluded that the fed pyruvate only very partially replaced internal substrates and that it was oxidized in a tricarboxylic acid cycle. It gave rise to alanine by direct amination and to other amino acids after partial oxidation. No pyruvate was built back to sugars or other carbohydrates in either tissue.

METABOLISM OF C14 AMINO ACIDS AND AMIDES IN DETACHED LEAVES

1956 ◽  
Vol 34 (4) ◽  
pp. 423-433 ◽  
Author(s):  
C. D. Nelson ◽  
G. Krotkov
Keyword(s):  
Amino Acids ◽  
Double Bond ◽  
Glutamic Acid ◽  
Broad Bean ◽  
Specific Activity ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Activity Data ◽  
Acid Cycle ◽  
Bean Leaves

Detached broad bean leaves were placed with their petioles in 0.01 M ammonium nitrate and allowed to carry on photosynthesis in C14O2 for various periods from 12 to 125 min. The radioactivities of the various amino acids formed from C14O2 were determined. In addition, these amino acids were degraded by decarboxylation with ninhydrin. From the specific activity data it was concluded that the amino acid closest to the site of carbon dioxide fixation in photosynthesis was alanine, followed by aspartic and glutamic acids, with the amides farthest removed. From the intramolecular distribution of label it was concluded that asparagine and glutamine were formed from their corresponding amino acids. The labelling in aspartic and glutamic acids was not consistent with the view that these two amino acids are formed from their corresponding α-keto acids produced by operation of the conventional tricarboxylic acid cycle. A C2 plus C2 condensation is postulated for the formation of aspartic acid. A shift in the double bond in the aconitase reaction of the tricarboxylic acid cycle would account for the observed labelling in glutamic acid. When acetate-1-C14 was fed to detached broad bean leaves in the light or dark, the distribution of label in glutamic acid supported the suggestion that there is such a. shift in the double bond in the aconitase reaction. Sodium arsenite, infiltrated into tobacco leaves, inhibited the biosynthesis of asparagine but not that of glutamine.

scholarly journals Metabolic control and regulation of the tricarboxylic acid cycle in photosynthetic and heterotrophic plant tissues

2011 ◽  
Vol 35 (1) ◽  
pp. 1-21 ◽  
Author(s):  
WAGNER L. ARAÚJO ◽  
ADRIANO NUNES-NESI ◽  
ZORAN NIKOLOSKI ◽  
LEE J. SWEETLOVE ◽  
ALISDAIR R. FERNIE
Keyword(s):  
Metabolic Control ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Plant Tissues ◽  
Acid Cycle

scholarly journals Neuronal-glial metabolism under depolarizing conditions. A 13C-n.m.r. study

1992 ◽  
Vol 282 (1) ◽  
pp. 225-230 ◽  
Author(s):  
R S Badar-Goffer ◽  
O Ben-Yoseph ◽  
H S Bachelard ◽  
P G Morris
Keyword(s):  
Amino Acids ◽  
Glial Cells ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
Maximum Percentage ◽  
Theoretical Maximum ◽  
Metabolic Pool ◽  
Time Courses ◽  
The Individual

Time courses of incorporation of 13C from 13C-labelled glucose and/or acetate into the individual carbon atoms of amino acids, citrate and lactate in depolarized cerebral tissues were monitored by using 13C-n.m.r. spectroscopy. There was no change in the maximum percentage of 13C enrichments of the amino acids on depolarization, but the maxima were reached more rapidly, indicating that rates of metabolism in both glycolysis and the tricarboxylic acid cycle were accelerated. Although labelling of lactate and of citrate approached the theoretical maximum of 50%, labelling of the amino acids was always below 20%, suggesting that there is a metabolic pool or compartment that is inaccessible to exogenous substrates. Under resting conditions labelling of citrate and of glutamine from [1-13C]glucose was not detected, whereas both were labelled from [2-13C]acetate, which is considered to reflect glial metabolism. In contrast, considerable labelling of these two metabolites from [1-13C]glucose was observed in depolarized tissues, suggesting that the increased metabolism may be due to increased consumption of glucose by glial cells. The labelling patterns on depolarization from [1-13C]glucose alone and from both precursors [( 1-13C]glucose plus [2-13C]acetate) were similar, which also indicates that the changes are due to increased consumption of glucose rather than acetate.

Studies in the respiratory and carbohydrate metabolism of plant tissues XIII. The influence of oxygen at high pressures in increasing and decreasing the respiration of potatoes at 15 °C

1963 ◽  
Vol 158 (971) ◽  
pp. 143-155 ◽  
Keyword(s):  
Carboxylic Acid ◽  
Carbohydrate Metabolism ◽  
High Pressures ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Total Carbon ◽  
Plant Tissues ◽  
Sugar Phosphate ◽  
Oxygen Inhibition ◽  
Acid Cycle

The CO 2 output of potatoes held at 15 °C in oxygen at a pressure of either 2 or 3 atm was first decreased, then increased and finally again decreased. The increase of CO 2 output was much larger than in carrots (Barker 1961); in oxygen at a pressure of 2 atm the rate of CO 2 output of potatoes was increased 4.6 fold; taking into account the accumulation of citrate, the ‘total carbon traffic’ was increased 5.6 fold in oxygen. This increase was believed to occur mainly in a pathway which was not the tricarboxylic acid cycle. As in potatoes held at 1 °C in an atmosphere of oxygen (Barker & Mapson 1955), citrate accumulated and α -ketoglutarate decreased in potatoes, held at 15 °C in oxygen at pressures of 2 or 3 atm; these changes were accepted as demonstrating the occurrence of the tri­-carboxylic acid cycle. The final decrease of CO 2 output in oxygen appeared not to be related to the occurrence of ‘blocks’ either between citrate and α -ketoglutarate or of pyruvate or α -ketoglutarate oxidases; the inhibition might be due to a shortage of sugar phosphate substrates, caused possibly by oxygen inhibition of cytochrome- c reductase. The outburst of CO 2 , which occurred in potatoes first held in oxygen and then returned to air, could not be attributed solely to oxidation of accumulated citrate.

scholarly journals Effect of renal tubule-specific knockdown of the Na+/H+exchanger NHE3 in Akita diabetic mice

2019 ◽  
Vol 317 (2) ◽  
pp. F419-F434 ◽  
Author(s):  
Akira Onishi ◽  
Yiling Fu ◽  
Manjula Darshi ◽  
Maria Crespo-Masip ◽  
Winnie Huang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Tricarboxylic Acid Cycle ◽  
Branched Chain Amino Acids ◽  
Tricarboxylic Acid ◽  
Proximal Tubules ◽  
Wild Type ◽  
Kidney Weight ◽  
Acid Cycle ◽  
Branched Chain

Na+/H+exchanger isoform 3 (NHE3) contributes to Na+/bicarbonate reabsorption and ammonium secretion in early proximal tubules. To determine its role in the diabetic kidney, type 1 diabetic Akita mice with tubular NHE3 knockdown [Pax8-Cre; NHE3-knockout (KO) mice] were generated. NHE3-KO mice had higher urine pH, more bicarbonaturia, and compensating increases in renal mRNA expression for genes associated with generation of ammonium, bicarbonate, and glucose (phosphoenolpyruvate carboxykinase) in proximal tubules and H+and ammonia secretion and glycolysis in distal tubules. This left blood pH and bicarbonate unaffected in nondiabetic and diabetic NHE3-KO versus wild-type mice but was associated with renal upregulation of proinflammatory markers. Higher renal phosphoenolpyruvate carboxykinase expression in NHE3-KO mice was associated with lower Na+-glucose cotransporter (SGLT)2 and higher SGLT1 expression, indicating a downward tubular shift in Na+and glucose reabsorption. NHE3-KO was associated with lesser kidney weight and glomerular filtration rate (GFR) independent of diabetes and prevented diabetes-associated albuminuria. NHE3-KO, however, did not attenuate hyperglycemia or prevent diabetes from increasing kidney weight and GFR. Higher renal gluconeogenesis may explain similar hyperglycemia despite lower SGLT2 expression and higher glucosuria in diabetic NHE3-KO versus wild-type mice; stronger SGLT1 engagement could have affected kidney weight and GFR responses. Chronic kidney disease in humans is associated with reduced urinary excretion of metabolites of branched-chain amino acids and the tricarboxylic acid cycle, a pattern mimicked in diabetic wild-type mice. This pattern was reversed in nondiabetic NHE3-KO mice, possibly reflecting branched-chain amino acids use for ammoniagenesis and tricarboxylic acid cycle upregulation to support formation of ammonia, bicarbonate, and glucose in proximal tubule. NHE3-KO, however, did not prevent the diabetes-induced urinary downregulation in these metabolites.

scholarly journals Metabolism of Lactate in Cultured GABAergic Neurons Studied by 13C Nuclear Magnetic Resonance Spectroscopy

1998 ◽  
Vol 18 (1) ◽  
pp. 109-117 ◽  
Author(s):  
Helle S. Waagepetersen ◽  
Inger J. Bakken ◽  
Orla M. Larsson ◽  
Ursala Sonnewald ◽  
Arne Schousboe
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Resonance Spectroscopy ◽  
Acid Cycle ◽  
Cell Extracts ◽  
Gaba Synthesis ◽  
Nuclear Magnetic

Primary cultures of mouse cerebral cortical neurons (GABAergic) were incubated for 4 hours in media without glucose containing 1.0 mmol/L [U-13C]lactate in the absence or presence of 0.5 mmol/L glutamine. Redissolved, lyophilized cell extracts were analyzed by 13C nuclear magnetic resonance spectroscopy to investigate neuronal metabolism of lactate and by HPLC for determination of the total amounts of glutamate (Glu), γ-aminobutyric acid (GABA), and aspartate (Asp). The 13C nuclear magnetic resonance spectra of cell extracts exhibited multiplets for Glu, GABA, and Asp, indicating pronounced recycling of labeled tricarboxylic acid cycle constituents. There was extensive incorporation of 13C label into amino acids in neurons incubated without glutamine, with the percent enrichments being approximately 60% for Glu and Asp, and 27% for GABA. When 0.5 mmol/L glutamine was added to the incubation medium, the enrichments for Asp, Glu, and GABA were 25%, 35%, and 25%, respectively. This strongly suggests that glutamine is readily converted to Glu and Asp but that conversion to GABA may be complex. The observation that enrichment in GABA was identical in the absence and presence of glutamine whereas cycling was decreased in the presence of glutamine indicates that only C-2 units derived from glutamine are used for GABA synthesis, that is, that metabolism through the tricarboxylic acid cycle is a prerequisite for GABA synthesis from glutamine. The current study gives further support to the hypothesis that cellular metabolism is compartmentalized and that lactate is an important fuel for neurons in terms of energy metabolism and extensively labels amino acids synthesized from tricarboxylic acid cycle intermediates (Asp and Glu) as well as the neurotransmitter in these neurons (GABA).

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.

AN ANOMALOUS TRICARBOXYLIC ACID CYCLE IN ACETOBACTER MELANOGENUM

1960 ◽  
Vol 38 (3) ◽  
pp. 193-203 ◽  
Author(s):  
D. H. Bone ◽  
R. M. Hochster
Keyword(s):  
Specific Activity ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
Oxidase System ◽  
Isocitric Dehydrogenase ◽  
Highly Active ◽  
Carbon Compounds ◽  
Condensing Enzyme

Extracts of gluconate-grown Acetobacter melanogenum contain condensing enzyme and DPN-isocitric dehydrogenase of low specific activity. No evidence could be found for the presence of phosphotransacetylase, aconitase, or TPN-isocitric dehydrogenase. Since the organism or its extracts cannot synthesize the necessary four carbon compounds from pyruvate and from acetate, it is concluded that the tricarboxylic acid cycle does not function in extracts of this organism in the usually accepted manner.The pyruvic oxidase system was found to be highly active, acetaldehyde being the chief intermediate and acetate the end product. The mechanism for the slow incorporation of acetate into other cell constituents is, at present, unknown.

More Than Skin Deep

2018 ◽  
Author(s):  
David R. Dalton
Keyword(s):  
Amino Acids ◽  
Nucleic Acids ◽  
Carboxylic Acids ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Grape Berry ◽  
Acid Cycle ◽  
Solid Portion ◽  
Present Complex ◽  
The Individual

The grape berry is composed of skin, flesh (pulp) and seeds. After destemming (Chapter 13), the grapes are sent on for crushing. On crushing, the thick walls of the skin, including the waxy cuticle, are broken. Crushing the grapes (Figure 16.1) is a question of quantity. Small quantities are handled differently than large. The skins, including the contaminants thereon, as well as the majority of the materials discussed above for the individual grapes (i.e., phenols, anthocyanins, tanins, some acids, terpenes, pyrazines, and some carbohydrates including those attached to the anthocyanidins, forming anthocyanins) therein, are released. The cells of the pulp are also broken and released into the juice on crushing. This berry cell juice is mainly water (70–80% by weight) which contains the mixture of sugars (mostly glucose and fructose, but small concentrations of many other carbohydrates are also present), carboxylic acids (mostly tartaric and malic, but additional members of the tricarboxylic acid cycle, oxalic, glucuronic, etc. are also present), complex cross-linked polysaccharides from cell walls (pectins), some phenols and proteins (as well as the peptides and simple amino acids from which they are constructed), and minerals, including oxides of iron (Fe), phosphorus (P), and sulfur (S), as well as salts of potassium (K) and sodium (Na) brought up in the xylem to the growing berry. The seeds have their cellulose carbohydrate-based exterior coatings, which are also rich in complexed polyphenols (tannins). Additionally, amino acids, generally found as constituents of peptides, proteins, and enzymes, and their cofactors needed for all life, nucleic acids and their attached sugars needed for the next generation, are all present too. Thus, overall, the result of crushing the berries is a mixture consisting of skins, seeds, and fruit juice (the must = Latin vinum mustum = young wine). This mixture may, if the grapes were “white,” be cooled and the cap on the must—sometimes called the pomace (the solid portion of the must) removed early or late (usually between 12 and 24 hours) by the vintner. Most of the flavoring constituents are quickly extracted, and brightly colored phenols, tannins, anthocyanins, etc.

Sign in / Sign up

Export Citation Format

Share Document