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.

Studies in the respiratory and carbohydrate metabolism of plant tissues - IX. Experimental studies of the influence of oxygen at high pressures on the respiration of apples and of a 'block' in the tricarboxylic acid cycle induced by 'oxygen poisoning'

1960 ◽  
Vol 152 (946) ◽  
pp. 88-108 ◽  
Keyword(s):  
Carbohydrate Metabolism ◽  
High Pressures ◽  
Tricarboxylic Acid Cycle ◽  
Experimental Studies ◽  
Tricarboxylic Acid ◽  
Plant Tissues ◽  
Acid Cycle ◽  
Marked Inhibition ◽  
Oxygen Poisoning

In contrast with peas (Turner & Quartley 1956; Pritchard 1959) apples treated with oxygen at pressures of 2½ or 5 atm showed complex changes with time in the rate of CO 2 output. These changes appeared to be due to the opposed effects of inhibitory and stimulatory processes; the latter caused a large increase in the rate of respiration in oxygen as compared with that of samples held in air. Although then the observed rate of CO 2 output after several days in oxygen was, in general, only a little slower than the rate in air, taking into account the increased rate of respiration in oxygen, there was in fact a marked inhibition of a part or parts of the respiratory process. There was also an accumulation in oxygen of pyruvate, alcohol and citrate and a decrease in the contents of α -ketoglutarate and oxaloacetate, as compared with apples in air. As in the earlier work with potatoes and peas (Barker & Mapson 1955; Turner & Quartley 1956), these changes in the acids were attributed in part to the production of an enzymic ‘block’ in the tricarboxylic acid cycle between citrate and α -ketoglutarate. The indication in previous work (Allentoff, Phillips & Johnston 1954) that the tricarboxylic acid cycle may operate in apples was thus supported. The paper includes data on the influence of a return to air at a pressure of one atmosphere following subjection to oxygen at high pressures.

Studies in the respiratory and carbohydrate metabolism of plant tissues - X. The influence of oxygen at high pressures as a stimulant and inhibitor of certain pathways of respiration in carrots

1961 ◽  
Vol 154 (956) ◽  
pp. 289-308 ◽  
Keyword(s):  
High Pressures ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
High Oxygen ◽  
Total Carbon ◽  
Inhibitory Effects ◽  
Acid Cycle ◽  
Concentration Changes ◽  
Oxygen Poisoning

In contrast with the behaviour of peas (Turner & Quartley 1956; Pritchard 1959, 1961) but like that of various tissues (Johannsen 1888; Cass 1947; Barker, Quartley & Turner 1960), the rate of CO 2 output of whole carrots was stimulated initially in oxygen at a pressure of 5 atm prior to the strong inhibition characteristic of oxygen poisoning. The inhibition was associated with an accumulation of citrate together with a decrease in the contents of α -ketoglutarate, succinate, malate and oxaloacetate; later pyruvate, alcohol and acetate also increased. As in the earlier work with potatoes, peas and apples (Barker & Mapson 1955; Turner & Quartley 1956; Barker et al . 1960), these changes in the acids were attributed in part to the production of an enzymic ‘block’ first in the tricarboxylic acid cycle between citrate and α -ketoglutarate and later in the oxidation of pyruvate. The earlier observations of the activity of the tricarboxylic acid cycle in carrot slices were thus confirmed (Pritchard 1959; ap Rees & Beevers 1960). The ‘total carbon traffic’, representing the sum of the observed CO 2 output in high oxygen and the calculated amounts of CO 2 that would be derived by oxidation of the accumulations of citrate, pyruvate, alcohol and acetate, increased initially in high oxygen to a rate which was about double that of the CO 2 output in air. Considered in relation to this increased carbon traffic in respiration, there was thus initially in high oxygen a large inhibition of the CO 2 output. Oxygen at high pressures thus produced simultaneous stimula­tory and inhibitory effects on certain phases of the respiratory process in carrots. Initially in high oxygen only a small part of the CO 2 output could be accounted for by the observed concentration changes: e. g. the accumulation of citrate; a part of the ‘unknown’ CO 2 output is provisionally attributed, without direct evidence, to operation of the pentose phosphate pathway, earlier shown to be active in carrot slices (Beevers & Gibbs 1954; ap Rees & Beevers 1960).

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

Carbohydrate metabolism in Acanthamoeba castellanii. 1. The activity of key enzymes and [14C]-glucose metabolism

1973 ◽  
Vol 19 (9) ◽  
pp. 1131-1136 ◽  
Author(s):  
Lansing M. Prescott ◽  
Harold E. Hoyme ◽  
Darlene Crockett ◽  
Elena Hui
Keyword(s):  
Carbohydrate Metabolism ◽  
Citrate Synthase ◽  
Tricarboxylic Acid Cycle ◽  
Fumarate Hydratase ◽  
Acanthamoeba Castellanii ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Acid Cycle ◽  
Key Enzymes ◽  
Glyceraldehydephosphate Dehydrogenase

The specific activities of a number of the key enzymes involved in carbohydrate metabolism in Acanthamoeba castellanii (Neff clone I–12) have been determined. The following Embden–Meyerhof and pentose phosphate pathway enzymes were present: glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, hexokinase, phosphofructokinase, hexose diphosphatase, aldolase, glyceraldehydephosphate dehydrogenase, pyruvate kinase, and pyruvate-phosphate dikinase. The following tricarboxylic acid cycle enzymes were also found: citrate synthase, aconitase, isocitrate dehydrogenase, succinate dehydrogenase, fumarate hydratase, and malate dehydrogenase. The degradation of glucose-U-14C to 14CO2 was examined. Aerobic 14CO2 production from glucose-U-14C was 3.4-fold greater than anaerobic production. The data provide further evidence that the Embden–Meyerhof, pentose phosphate, and tricarboxylic acid cycle pathways are probably functional in A. castellanii.

Effect ofEchinococcus multilocularison the origin of acetyl-CoA entering the tricarboxylic acid cycle in host liver

2002 ◽  
Vol 76 (1) ◽  
pp. 31-36 ◽  
Author(s):  
C. Kepron ◽  
M. Novak ◽  
B.J. Blackburn
Keyword(s):  
Carbohydrate Metabolism ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Meriones Unguiculatus ◽  
Host Liver ◽  
Acetyl Coa ◽  
Acid Cycle ◽  
A Value ◽  
Alveolar Hydatid Disease ◽  
And Control

AbstractCarbon-13 nuclear magnetic resonance (NMR) spectroscopy was employed to investigate alterations in hepatic carbohydrate metabolism inMeriones unguiculatusinfected withEchinococcus multilocularis. Following portal vein injections of an equimolar mixture of ]#x005B;1,2-13C2]acetate and [3-13C]lactate, perchloric acid extracts of the livers were prepared and NMR spectra obtained. Isotopomer analysis using glutamate resonances in these spectra showed that the relative contributions of endogenous and exogenous substrates to the acetyl-CoA entering the tricarboxylic acid cycle differed significantly between infected and control groups. The mole fraction of acetyl-CoA that was derived from endogenous, unlabelled sources (FU) was 0.50±0.10 in controls compared to 0.34±0.04 in infected animals. However, the fraction of acetyl-CoA derived from [3-13C]lactate (FLL) was larger in livers of infected animals than those from controls with values of 0.27±0.04 and 0.18±0.04, respectively. Similarly, the fraction of acetyl-CoA derived from [1,2-13C2]acetate (FLA) was larger in livers of infected animals compared to those in controls; the fractions were 0.38±0.01 and 0.32±0.07, respectively. The ratio of FLA:FLLwas significantly smaller in the infected group with a value of 1.42±0.18 compared to 1.74±0.09 for the controls. These results indicate that alveolar hydatid disease has a pronounced effect on the partitioning of substrates within the pathways of carbohydrate metabolism in the host liver.

Intermediary carbohydrate metabolism in protoscoleces ofEchinococcus granulosus(horse and sheep strains) andE. multilocularis

Parasitology ◽  
1982 ◽  
Vol 84 (2) ◽  
pp. 351-366 ◽  
Author(s):  
D. P. McManus ◽  
J. D. Smyth
Keyword(s):  
Steady State ◽  
Carbohydrate Metabolism ◽  
Pyruvate Kinase ◽  
Energy Production ◽  
Alternative Energy ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Acid Cycle ◽  
State Content

SUMMARYWith few exceptions, the specific activities of the glycolytic enzymes and the steady-state content of glycolytic and associated intermediates in protoscoleces of the horse (E.g.H) and sheep (E.g.S) strains ofEchinococcus granulosusand the closely relatedE. multilocularis(E.m.) are very similar. Phosphorylase, hexokinase, phosphofructokinase and pyruvate kinase catalyse non-equilibrium reactions and the patterns of activity for pyruvate kinase, phosphoenolpyruvate carboxykinase and malic enzyme are similar in the three organisms. The levels of tricarboxylic acid cycle intermediates inE.g.H., E.g.S. andE.m. are of the same order as those reported in tissues with an active cycle. Each has a complete sequence of cycle enzymes but there are substantial differences between the three parasites with regard to the activity of individual enzymes, The activities of NAD and NADP-linked isocitrate dehydrogenases are significantly lower inE.g.H. than inE.g.S. and particularly inE.m. which suggests that the tricarboxylic acid cycle may play a more important role in carbohydrate metabolism and energy production in the latter parasites. Nevertheless, the three organisms utilize fermentative pathways for alternative energy production, fix carbon dioxide via phosphoenolpyruvate carboxykinase and have a partial reversed tricarboxylic acid cycle. It is speculated thatin vivomore carbon will be channelled towards oxaloacetate than pyruvate at the phosphoenolpyruvate branch point. The steady state content of ATP and the ATP/AMP ratios are low in the three organisms, suggesting a low rate of ATP utilization in each.

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.

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