Compartments of organic acids in the synthesis of asparagine and homoserine in pea roots

1970 ◽  
Vol 48 (11) ◽  
pp. 2001-2007 ◽  
Author(s):  
D. J. Mitchell ◽  
R. G. S. Bidwell
Keyword(s):  
Organic Acids ◽  
Krebs Cycle ◽  
Carbon Precursor ◽  
Metabolic System ◽  
Pea Root ◽  
Carbon Acids ◽  
Pea Roots ◽  
Carbon Acid

14C-Labeled aspartate and organic acids were supplied to pea-root pieces to elucidate the pathways of carbon leading to asparagine and homoserine synthesis. The pattern of labeling in the products, and the effects of competing non-radioactive acids on the distribution of 14C from labeled substrates, gave the following results. Supplied aspartate is not converted directly to asparagine or homoserine, but must first enter the Krebs cycle. If aspartate is an immediate precursor of either of these compounds, the synthetic pathways must be compartmented from externally supplied aspartate. Carbon leaves the Krebs cycle as succinate, and is converted to other 4-carbon acids in a metabolic system that is separated from the Krebs cycle and presumably outside the mitochondria. The pathway from succinate to homoserine proceeds via extramitochondrial fumarate and malate, and to asparagine via fumarate. Carboxylation of pyruvate (or a related three-carbon acid) leads to homoserine and asparagine via a symmetrical intermediate permitting equilibration of the two ends of the 4-carbon precursor. About four times more carbon from added pyruvate is converted to homoserine and asparagine via the Krebs cycle than by carboxylation.

THE EFFECTS OF INDOLEACETIC ACID AND 2, 4-DICHLOROPHENOXYACETIC ACID ON INTERMEDIARY METABOLISM OF 14C-LABELLED ORGANIC ACIDS BY PEA ROOT TIPS

1967 ◽  
Vol 45 (10) ◽  
pp. 1789-1796 ◽  
Author(s):  
W. K. Kim ◽  
R. G. S. Bidwell
Keyword(s):  
Amino Acids ◽  
Organic Acids ◽  
Pyruvic Acid ◽  
Indoleacetic Acid ◽  
Krebs Cycle ◽  
Dichlorophenoxyacetic Acid ◽  
Root Tips ◽  
Specific Effects ◽  
Pea Root ◽  
Krebs Cycle Intermediates

The effects of indoleacetic acid (IAA) and 2, 4-dichlorophenoxyacetic acid (2, 4-D) on the metabolism of 14C-specifically labelled pyruvic, acetic, succinic, and glutamic acids by pea root tips have been examined. The conversion of 14C from the substrates into alcohol-soluble and -insoluble fractions and respired CO2 was determined, and the radioactivity of certain soluble amino acids and organic acids was measured after chromatography. While pyruvic acid decarboxylation is unaffected, the carboxylation of pyruvic acid and the entry into the Krebs cycle of acetate derived from pyruvate is inhibited by the hormones. Acetate, however, is oxidized to CO2 much more rapidly in the presence of IAA or 2, 4-D. The accumulation of 14C in Krebs cycle intermediates or amino acids derived from them is prevented by the auxins. The results indicate that IAA and 2, 4-D have an inhibiting effect either on co-carboxylase or more likely on α-lipoic acid metabolism, but not on coenzyme A (CoA). Other specific effects on the metabolism of individual amino acids are also indicated.

scholarly journals Acetate represents a major product of heptanoate and octanoate β-oxidation in hepatocytes isolated from neonatal piglets

1996 ◽  
Vol 318 (1) ◽  
pp. 235-240 ◽  
Author(s):  
Xi LIN ◽  
Sean H. ADAMS ◽  
Jack ODLE
Keyword(s):  
Fatty Acid ◽  
Organic Acids ◽  
Chain Length ◽  
Ketone Bodies ◽  
Krebs Cycle ◽  
Major Product ◽  
Carbon Accounting ◽  
Minor Amount ◽  
Fatty Acid Carbon ◽  
Carboxyl Carbon

An experiment was conducted to explore the nature of the radiolabel distribution in acid-soluble products (ASPs) resulting from the oxidation of [1-14C]C7:0 or C8:0 by isolated piglet hepatocytes. The differences between odd and even chain-length and the impacts of valproate and malonate upon the rate of β-oxidation and ASP characteristics were tested. A minor amount of fatty acid carboxyl carbon (⩽ 10% of organic acids identified by radio-HPLC) accumulated in ketone bodies regardless of chain-length or inhibitor used. In all cases, acetate represented the major reservoir of carboxyl carbon, accounting for 60–70% of radiolabel in identified organic acids. Cells given [1-14C]C7:0 accumulated 85% more carboxyl carbon in Krebs cycle intermediates when compared with C8:0, while accumulation in acetate was unaffected. The results are consistent with the hypothesis that anaplerosis from odd-carbon fatty acids affects the oxidative fate of fatty acid carbon. The piglet appears unique in that non-ketogenic routes of fatty acid carbon flow (i.e. acetogenesis) predominate in the liver of this species.

On dissociation of weak dibasic and tribasic organic acids participating in Krebs cycle

2009 ◽  
Vol 45 (2) ◽  
pp. 221-224 ◽  
Author(s):  
R. K. Kvaratskhelia ◽  
E. R. Kvaratskhelia
Keyword(s):  
Organic Acids ◽  
Krebs Cycle

Excited state carbon acid dissociation and competing photorearrangements of 5H-dibenzo[a,c]cycloheptene derivatives

1996 ◽  
Vol 74 (8) ◽  
pp. 1447-1464 ◽  
Author(s):  
David. Budac. ◽  
Peter Wan
Keyword(s):  
Excited State ◽  
Fluorescence Quenching ◽  
Singlet State ◽  
Acid Dissociation ◽  
Excited Singlet ◽  
Deuterium Incorporation ◽  
Group A ◽  
Carbon Acids ◽  
Work Structure ◽  
Carbon Acid

The first examples of dissociating excited state carbon acids were reported by our group. A necessary structural feature is the 5H-dibenzocycloheptene ring system where the incipient carbanion is formally an antiaromatic system in S0. In this work, structure–reactivity studies of the excited singlet state carbon acid dissociation and competing formal di-π-methane rearrangement of several 5H-dibenzo[a,c]cycloheptene derivatives have been carried out in order to gain more insights into the photochemistry displayed by these compounds. Photolysis of 7-deuterio-5H-dibenzo[a,c]cycloheptene (9) in aqueous solution showed that the photogenerated carbanion is allylically delocalized. Derivative 7 was found to be less reactive than 3 with respect to carbon acid dissociation whereas 8 was unreactive. Ethanolamine (in CH3CN) was found to be an effective base in catalyzing carbon acid dissociation for 3, 7, and 9, as indicated by higher yields of deuterium incorporation and rates of fluorescence quenching. Binaphthyl derivatives 10 and 11 displayed contrasting photobehaviour. Photolysis of binaphthyl 11 resulted in only efficient (ΦP = 0.47) formal di-π-methane rearrangement under all conditions and no evidence was found for carbon acid dissociation, even in the presence of ethanolamine as base. On the other hand, the formal di-π-methane reaction was very inefficient for binaphthyl 10 (Φp < 0.001). Due to the conformational rigidity inherent in 10, the methylene protons at the 3-position are NMR resolvable as pseudo-axial and pseudo-equatorial protons. Photolysis in the presence of ethanolamine (in D2O–CH3CN) resulted in stereoselective deprotonation of the pseudo-axial proton (Φex ≈ 0.02), as indicated by deuterium exchange studies. The results show that excited state carbon acid dissociation is an observable general reaction of dibenzo and dinaphtho cycloheptenes only if more favourable photochemical pathways are not competing. Key words: excited state carbon acid, di-π-methane rearrangement, carbanion, stereoelectronic effect, fluorescence quenching.

scholarly journals Transcriptional and Metabolic Responses of Bacillus subtilis to the Availability of Organic Acids: Transcription Regulation Is Important but Not Sufficient To Account for Metabolic Adaptation

2006 ◽  
Vol 73 (2) ◽  
pp. 499-507 ◽  
Author(s):  
Oliver Schilling ◽  
Oliver Frick ◽  
Christina Herzberg ◽  
Armin Ehrenreich ◽  
Elmar Heinzle ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Organic Acids ◽  
Pentose Phosphate Pathway ◽  
Metabolic Regulation ◽  
Metabolic Flux ◽  
Krebs Cycle ◽  
Pentose Phosphate ◽  
Metabolic Adaptation ◽  
Acetyl Coa ◽  
Additional Level

ABSTRACT The soil bacterium Bacillus subtilis can use sugars or organic acids as sources of carbon and energy. These nutrients are metabolized by glycolysis, the pentose phosphate pathway, and the Krebs citric acid cycle. While the response of B. subtilis to the availability of sugars is well understood, much less is known about the changes in metabolism if organic acids feeding into the Krebs cycle are provided. If B. subtilis is supplied with succinate and glutamate in addition to glucose, the cells readjust their metabolism as determined by transcriptome and metabolic flux analyses. The portion of glucose-6-phosphate that feeds into the pentose phosphate pathway is significantly increased in the presence of organic acids. Similarly, important changes were detected at the level of pyruvate and acetyl coenzyme A (acetyl-CoA). In the presence of organic acids, oxaloacetate formation is strongly reduced, whereas the formation of lactate is significantly increased. The alsSD operon required for acetoin formation is strongly induced in the presence of organic acids; however, no acetoin formation was observed. The recently discovered phosphorylation of acetolactate decarboxylase may provide an additional level of control of metabolism. In the presence of organic acids, both types of analyses suggest that acetyl-CoA was catabolized to acetate rather than used for feeding the Krebs cycle. Our results suggest that future work has to concentrate on the posttranslational mechanisms of metabolic regulation.

scholarly journals The Mitotic Index of Cajanus cajan from Kisar Island, in the Southwest of Maluku

2021 ◽  
Vol 13 (2) ◽  
pp. 128-134
Author(s):  
Kristin Sangur ◽  
Alwi Smith ◽  
Meike Tomasoa
Keyword(s):  
Cell Division ◽  
Mitotic Index ◽  
Vegetative Reproduction ◽  
Pigeon Pea ◽  
Root Cell ◽  
Optimum Time ◽  
Root Cells ◽  
Carnoy’S Solution ◽  
Pea Root ◽  
Pea Roots

The mitotic index of the roots of pigeon pea can be the basis for determining the growth of pigeon pea. The purpose of this research was to determine the time of root cell division, to observe the mitotic phases, and to determine the mitotic index of pigeon pea root cells. The preparation of the pigeon pea was carried out for 4 days to grow the roots. The roots were cut off at 08.00, 08.15, and 08.30 WIT (Eastern Indonesian Time). The roots were cut 0.5-1cm. Carnoy’s solution was used as the fixative solution using the Squash technique. The prepared roots were then observed using an Olympus cx-22 microscope and an OptiLab camera with a magnification of 100x40. The data were descriptively analyzed to describe the images of mitotic phases and the mitotic index presentation in the root cells of pigeon pea. The results of this research showed that the cell division of the pigeon pea roots began at 08.00 WIT, which was marked by the presence of a lot of prophase. The next phases that appeared were prometaphase, metaphase, and anaphase which occurred from 08.15 to 08.30 with different numbers. The highest mitotic index occurred at 08.15, when most of the root cells underwent metaphase. This study succeeded in revealing that the optimum time for pigeon pea root cell division is 08.15 WIT. In the future, this research can help pigeon pea farmers in Southwest of Maluku to carry out vegetative reproduction which is closely related to this mitotic study.

Towards a complete account of the mechanism of hydrogen isotope exchange of diastereotopic protons of carbon acids. II. Acid- and base-catalyzed enolization of bicyclo[2.2.1]heptan-2-ones. Evidence for exchange by inversion

1985 ◽  
Vol 63 (2) ◽  
pp. 534-541 ◽  
Author(s):  
Nick Henry Werstiuk ◽  
Sujit Banerjee
Keyword(s):  
Hydrogen Isotope ◽  
Isotope Exchange ◽  
Significant Contribution ◽  
Hydrogen Isotope Exchange ◽  
Acid And Base ◽  
Carbon Acids ◽  
Acid Catalyzed ◽  
Rate Ratios ◽  
Carbon Acid ◽  
Complete Account

A study of acid- and base-catalyzed hydrogen isotope exchange of bicyclo[2.2.1]heptan-2-one (1a) and its 3-deuteriated analogs has been carried out. We find that the kexo/kendo ratio (658 ± 66) for deuteroxide-catalyzed H → D exchange of 1a at C-3 is 7.2 ± 1.5 times greater than the kexo/kendo ratio (91 ± 9) for hydroxide-catalyzed D → H exchange of 1b. For acid-catalyzed exchange in CH3COOD(H)–D(H)Cl the rate ratios are 156 ± 20 and 29 ± 2 for H → D and D → H exchange, respectively. Equations which relate the observed selectivity kexo/kendo (kfast/kslow) to the intrinsic selectivity and the primary, secondary, and solvent KIEs are developed. The differences between the rate ratios for H → D and D → H exchange are interpreted on the basis of a significant contribution of an inversion pathway to exchange of the slow proton (deuteron). The significance of our study – it relates to the mechanism of hydrogen isotope exchange of diastereotopic protons (deuterons, tritons) of any carbon acid – is discussed.

The effect of pea root exudate on the germination of Pythium aphanidermatum zoospore cysts

1970 ◽  
Vol 48 (9) ◽  
pp. 1501-1514 ◽  
Author(s):  
Yung Chang-Ho
Keyword(s):  
Organic Acids ◽  
Germ Tube ◽  
Root Exudate ◽  
Pythium Aphanidermatum ◽  
Tube Growth ◽  
Percentage Germination ◽  
Pea Root ◽  
Low Concentrations ◽  
Germination And Growth ◽  
Germ Tube Growth

Zoospore cysts of Pythium aphanidermatum germinated well without external nutrient supply, but pea root exudate increased percentage germination and germ tube growth. Zoospore cyst germination and growth varied with different concentrations of the substrate supplied. Alone, the neutral fraction (sugars) increased percentage germination but had little effect on germ tube growth; the cationic fraction (amino acids) suppressed germination and growth somewhat, except at very low concentrations; the anionic fraction (organic acids) mildly stimulated both processes. Neutral and anionic fractions combined approached the stimulatory effect of root exudate. Amongst the components of root exudate tested as pure chemicals, fructose, histidine, homoserine, proline, and tartaric acid promoted germination and growth at low concentrations. Alpha-alanine, glutamine, serine, and valine became stimulatory at high concentrations. A combination of glucose with one of the organic acids was more effective than either alone.

scholarly journals Glutamine and asparagine as nitrogen donors for reductant-dependent glutamate synthesis in pea roots

1975 ◽  
Vol 149 (2) ◽  
pp. 403-409 ◽  
Author(s):  
B J Miflin ◽  
P J Lea
Keyword(s):  
Glutamine Synthetase ◽  
Glutamate Synthase ◽  
Crude Extracts ◽  
Pea Root ◽  
Pea Roots ◽  
Nitrogen Donors ◽  
Glutamate Synthesis

Glutamine, in the presence of α-oxoglutarate, stimulates nicotinamide nucleotide oxidation by crude extracts of pea roots and leads to a reductant-dependent formation of glutamate. Commercially available asparagine also stimulates nicotinamide nucleotide oxidation in the presence of α-oxoglutarate, but the reaction causing the stimulation can occur in the absence of a reductant, is inhibited by transaminase inhibitors, and is additive to the glutamine reaction. The asparagine used was found to be contaminated with aspartate. Repurified asparagine, chromatographically free of aspartate, did not stimulate the rate of nicotinamide nucleotide oxidation, and it is probable that the original stimulation was due to aspartate contamination. It is concluded that pea-root glutamine (amide)-α-oxoglutarate aminotransferase (glutamate synthase), in common with the enzyme in leaves, is specific for glutamine as the N donor and α-oxoglutarate as the N acceptor. The significance of the enzyme in conjunction with glutamine synthetase in the assimilation of nitrate by roots is discussed.

scholarly journals Localizatlon of expansin-like protein in apoplast of pea (Pisum sativum L.) root nodules during interaction with Rhizobium leguminosarum bv. viciae

2011 ◽  
Vol 76 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Marzena Sujkowska ◽  
Wojciech Borucki ◽  
Władysław Golinowski
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Rhizobium Leguminosarum ◽  
Plant Cell Wall ◽  
Root Nodules ◽  
Infection Thread ◽  
Nodule Development ◽  
Cell Enlargement ◽  
Pea Root ◽  
Pea Roots

During nodule development on pea roots, apoplast undergoes changes in activity of plant cell wall proteins such as expansins (EXPs). Because the accumulation of EXP protein has been correlated with the growth of various plant organs, we investigated using Western Blot and immunolocalization studies with antibody against PsEXP1, whether this protein was accumulated in the expanding cells of nodule. Immunoblot results indicated the presence of a 30-kDa band specific for pea root nodules. The EXP proteins content rose during growth of pea root nodules. Expansin(s) protein was localized in nodule apoplast as well as in the infection thread walls. The enhanced amount of expansin-like proteins in meristematic part of nodule, root and shoot was shown. The localization of this protein in the meristematic cell walls can be related to the loosening of plant cell wall before cell enlargement. Both, plant cell enlargement and infection thread growth require activity of expansin(s). Possible involvement of EXPs in the process of pea root nodule development is also discussed.

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