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Light-Dependent And Tissue-Specific Expression Of The H-Protein Of The Glycine Decarboxylase Complex, R. Srinivasan, David J. Oliver
Light-Dependent And Tissue-Specific Expression Of The H-Protein Of The Glycine Decarboxylase Complex, R. Srinivasan, David J. Oliver
David J. Oliver
Glycine decarboxylase is a mitochondrial enzyme complex, which is the site of photorespiratory CO2 and NH3 release. Although the proteins that constitute the complex are located within the mitochondria, because of their intimate association with photosynthesis their expression is controlled by light. Comparisons of the kinetics of mRNA accumulation between the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase and the H-protein of glycine decarboxylase during the greening of etiolated Arabidopsis thaliana suggest that their expression is controlled in parallel. A genomic clone for the H-protein (gdcH) was isolated from Arabidopsis and sequenced. The upstream region from -856 to +62 was fused to …
The Phosphate Transporter From Pea Mitochondria (Isolation And Characterization In Proteolipid Vesicles), Cecilia A. Mcintosh, David J. Oliver
The Phosphate Transporter From Pea Mitochondria (Isolation And Characterization In Proteolipid Vesicles), Cecilia A. Mcintosh, David J. Oliver
David J. Oliver
The phosphate transporter from mitochondria will exchange matrix phosphate for cytosolic phosphate and facilitate either phosphate/proton symport or phosphate/hydroxyl ion antiport. The phosphate transported into the matrix by this carrier is either used for ATP synthesis or exchanges back out to the cytosol on the dicarboxylate transporter, permitting entry of malate and succinate into the matrix. The phosphate transporter was solubilized from etiolated pea (Pisum sativum L. cv Alaska) mitochondrial membranes with Triton X-114, purified approximately 500-fold by hydroxylapatite chromatography, and reconstituted into azolectin vesicles that were preloaded with 0.1 or 10 mM phosphate. Phosphate transport was measured as the …
Isolation And Characterization Of The Tricarboxylate Transporter From Pea Mitochondria, Cecilia A. Mcintosh, David J. Oliver
Isolation And Characterization Of The Tricarboxylate Transporter From Pea Mitochondria, Cecilia A. Mcintosh, David J. Oliver
David J. Oliver
The tricarboxylate transporter was solubilized from pea (Pisum sativum) mitochondria with Triton X-114, partially purified over a hydroxylapatite column, and reconstituted in phospholipid vesicles. The proteoliposomes exchanged external [14C]citrate for internal citrate or malate but not for preloaded D,L-isocitrate. Similarly, although external malate, succinate, and citrate competed with [14C]citrate in the exchange reaction, D,L-isocitrate and phosphoenolpyruvate did not. This tricarboxylate transporter differed from the equivalent activity from animal tissues in that it did not transport isocitrate and phosphoenolpyruvate. In addition, tricarboxylate transport in isolated plant mitochondria, as well as that measured with the partially purified and reconstituted transporter, was less …
Nad+-Linked Isocitrate Dehydrogenase: Isolation, Purification, And Characterization Of The Protein From Pea Mitochondria, Cecilia A. Mcintosh, David J. Oliver
Nad+-Linked Isocitrate Dehydrogenase: Isolation, Purification, And Characterization Of The Protein From Pea Mitochondria, Cecilia A. Mcintosh, David J. Oliver
David J. Oliver
The NAD+-dependent isocitrate dehydrogenase from etiolated pea (Pisum sativum L.) mitochondria was purified more than 200-fold by dye-ligand binding on Matrix Gel Blue A and gel filtration on Superose 6. The enzyme was stabilized during purification by the inclusion of 20% glycerol. In crude matrix extracts, the enzyme activity eluted from Superose 6 with apparent molecular masses of 1400 ± 200, 690 ± 90, and 300 ± 50 kD. During subsequent purification steps the larger molecular mass species disappeared and an additional peak at 94 ± 16 kD was evident. The monomer for the enzyme was tentatively identified at 47 …
H-Protein Of The Glycine Decarboxylase Multienzyme Complex: Complementary Dna Encoding The Protein From Arabidopsis Thaliana, David J. Oliver
H-Protein Of The Glycine Decarboxylase Multienzyme Complex: Complementary Dna Encoding The Protein From Arabidopsis Thaliana, David J. Oliver
David J. Oliver
The glycine decarboxylase multienzyme complex is composed of four component enzymes, the 100-kD P-protein (a pyridoxal 5-phosphate-dependent amino acid decarboxylase), the 14-kD H-protein (a lipoamide-containing carrier protein), the 45-kD T-protein (a tetrahydrofolate transferase), and the 59-kD L-protein (lipoamide dehydrogenase) (5). The Iipoamide cofactor of the H-protein carries reaction intermediates between the active sites of the other three component proteins. These proteins form a large molecular weight complex (4) within the matrix ofleaf mitochondria where, together with the enzyme serine hydroxymethyltransferase, it catalyzes the photorespiratory conversion of two molecules of glycine to one each of serine, NH3, and CO2 with the …
Interaction Between The Component Enzymes Of The Glycine Decarboxylase Multienzyme Complex, David J. Oliver, Michel Neuburger, Jacques Bourguignon, Roland Douce
Interaction Between The Component Enzymes Of The Glycine Decarboxylase Multienzyme Complex, David J. Oliver, Michel Neuburger, Jacques Bourguignon, Roland Douce
David J. Oliver
The glycine decarboxylase multienzyme complex comprises about one-third of the soluble protein of the matrix of pea (Pisum sativum) leaf mitochondria where it exists at a concentration of approximately 130 milligrams protein/milliliter. Under these conditions the complex is stable with an approximate subunit ratio of 2 P-protein dimers:27 H-protein monomers:9 T-protein monomers:1 L-protein dimer. When the complex is diluted it tends to dissociate into its component enzymes. This prevents the purification of the intact complex by gel filtration or ultracentrifugation. In the dissociated state the H-protein acts as a mobile cosubstrate that commutes between the other three enzymes and shows …
Isolation And Partial Characterization Of The Glutamate/Aspartate Transporter From Pea Leaf Mitochondria Using A Specific Monoclonal Antibody, Jeevalatha Vivekananda, David J. Oliver
Isolation And Partial Characterization Of The Glutamate/Aspartate Transporter From Pea Leaf Mitochondria Using A Specific Monoclonal Antibody, Jeevalatha Vivekananda, David J. Oliver
David J. Oliver
A library of monoclonal antibodies directed against the proteins of the inner mitochondrial membrane was screened for antibodies that could bind to the glutamate/aspartate transporter of pea mitochondria and thereby inhibit its activity. One antibody, 2C7, had the property of inhibiting glutamate and aspartate-dependent oxaloacetate metabolism by pea mitochondria without affecting the metabolism of other substrates. The antibody specifically recognized a 21,000 dalton protein, which was tentatively identified as the glutamate/aspartate transporter. The antibody was used to follow the extraction of this protein by Triton X-114 and cardiolipin and the partial purification of the protein by centrifugation and chromatography on …
An Electrochemical Method Of Measuring The Oxidation Rate Of Ferrous To Ferric Iron With Oxygen In The Presence Of Thiobacillus Ferrooxidans, David J. Oliver, B. Pesic, P. Wichlacz
An Electrochemical Method Of Measuring The Oxidation Rate Of Ferrous To Ferric Iron With Oxygen In The Presence Of Thiobacillus Ferrooxidans, David J. Oliver, B. Pesic, P. Wichlacz
David J. Oliver
The oxidation of Fe2+ with oxygen in sulfate solutions was studied in the presence of T. ferrooxidans. To measure the chemical activity of bacteria, and the oxidation rate of iron, the redox potentials of solutions were continuously monitored during the experiments. The redox potentials were simultaneously monitored on the platinum and pyrite indicator electrodes. The redox potential versus time curves were further used to calculate the basic kinetic parameters, such as the reaction orders, the activation energy, and the frequency factor. It was found that under atmospheric conditions, and at Fe2+ < 0.001M, T < 25°C, and at pH above 2.2, the oxidation of iron is governed by the following rate expression: [equation image] Below pH = 2.2, the oxidation rate is independent of H+ Concentration.
Inhibition Of Glycine Oxidation By Carboxymethoxylamine, Methoxylamine, And Acethydrazide, G. Sarojini, David J. Oliver
Inhibition Of Glycine Oxidation By Carboxymethoxylamine, Methoxylamine, And Acethydrazide, G. Sarojini, David J. Oliver
David J. Oliver
Carboxymethoxylamine (amino-oxyacetate), methoxylamine, and acethydrazide are shown to be effective, although not completely specific, inhibitors of glycine oxidation by the isolated glycine decarboxylase multienzyme complex, mitochondria, protoplasts, and leaf discs from peas. The inhibition probably results from a reaction between these compounds and the pyridoxal 5-phosphate cofactor of the enzyme.
Characterization Of The Transport Of Oxaloacetate By Pea Leaf Mitochondria, David J. Oliver, Griffin H. Walker
Characterization Of The Transport Of Oxaloacetate By Pea Leaf Mitochondria, David J. Oliver, Griffin H. Walker
David J. Oliver
Mitochondria isolated from pea (Pisum sativum L.) leaves are able to transport the keto acid, oxaloacetate, from the reaction medium into he mitochondrial matrix at high rates. The rate of uptake by the mitochondria was measured as the rate of disappearance of oxaloacetate from the reaction medium as it was reduced by matrix malate dehydrogenase using NADH provided by glycine oxidation. The oxaloacetate transporter was identifed as being distinct from the dicarboxylate and the α-ketoglutarate transporters because of its inhibitor sensitivities and its inability to interact with other potential substrates. Phthalonate and phthalate were competitive inhibitors of oxaloacetate transport with …
Extraction And Partial Characterization Of The Glycine Decarboxylase Multienzyme Complex From Pea Leaf Mitochondria, G. Sarojini, David J. Oliver
Extraction And Partial Characterization Of The Glycine Decarboxylase Multienzyme Complex From Pea Leaf Mitochondria, G. Sarojini, David J. Oliver
David J. Oliver
Glycine decarboxylase has been successfully solubilized from pea (Pisum sativum) leaf mitochondria as an acetone powder. The enzyme was dependent on added dithiothreitol and pyridoxal phosphate for maximal activity. The enzyme preparation could catalyze the exchange of CO2 into the carboxyl carbon of glycine, the reverse of the glycine decarboxylase reaction by converting serine, NH4+, and CO2 into glycine, and 14CO2 release from [1-14C]glycine. The half-maximal concentrations for the glycine-bicarbonate exchange reaction were 1.7 millimolar glycine, 16 millimolar NaH14CO2, and 0.006 millimolar pyridoxal phosphate. The enzyme (glycine-bicarbonate exchange reaction) was active in the assay conditions for 1 hour and could …
Simultaneous Oxidation Of Glycine And Malate By Pea Leaf Mitochondria, Griffin H. Walker, David J. Oliver, G. Sarojini
Simultaneous Oxidation Of Glycine And Malate By Pea Leaf Mitochondria, Griffin H. Walker, David J. Oliver, G. Sarojini
David J. Oliver
Mitochondria isolated from pea leaves (Pisum sativum L.) readily oxidized malate and glycine as substrates. The addition of glycine to mitochondria oxidizing malate in state 3 diminished the rate of malate oxidation. When glycine was added to mitochondria oxidizing malate in state 4, however, the rate of malate oxidation was either unaffected or stimulated. The reason both glycine and malate can be metabolized in state 4 appears to be that malate only used part of the electron transport capacity available in these mitochondria in this state. The remaining electron transport capacity was used by glycine, thus allowing both substrates to …
Role Of Glycine And Glyoxylate Decarboxylation In Photorespiratory Co2 Release, David J. Oliver
Role Of Glycine And Glyoxylate Decarboxylation In Photorespiratory Co2 Release, David J. Oliver
David J. Oliver
Mechanically isolated soybean leaf cells metabolized added glycolate by two mechanisms, the direct oxidation of glyoxylate and the decarboxylation of glycine. The rate of glyoxylate oxidation was dependent on the cellular glyoxylate concentration and was linear between 0.58 and 2.66 micromoles glyoxylate per milligram chlorophyll. The rate extrapolated to zero at a concentration of zero. The concentration and, therefore, the rate of oxidation of glyoxylate could be decreased by adding glutamate or serine to the cells. These substrates were amino donors for the transamination of glyoxylate to glycine. In the presence of these amino acids more CO2 was released from …
Formate Oxidation And Oxygen Reduction By Leaf Mitochondria, David J. Oliver
Formate Oxidation And Oxygen Reduction By Leaf Mitochondria, David J. Oliver
David J. Oliver
Mitochondria isolated from the leaves of several plant species were investigated for the presence of NAD-linked formate dehydrogenase. The NADH produced was oxidized by the electron transport sequence and was coupled to ATP synthesis. The amounts of formate dehydrogenase, and, thereby, the capacity for formate-dependent O2 uptake, varied greatly among species. While no activity was detectable in mitochondria from soybean leaves, the rate of formate oxidation by spinach mitochondria was about one-half the rate of malate oxidation. In spinach, only mitochondria from green tissues oxidized formate. These last two observations raise questions as to the role of this reaction and …
The Effect Of Glyoxylate On Photosynthesis And Photorespiration By Isolated Soybean Mesophyll Cells, David J. Oliver
The Effect Of Glyoxylate On Photosynthesis And Photorespiration By Isolated Soybean Mesophyll Cells, David J. Oliver
David J. Oliver
Incubating isolated soybean leaf mesophyll cells with glyoxylate increased the rates of CO2 fixation by as much as 150%. In order to cause this stimulation, the glyoxylate must be presented to the cells before the NaHCO3. Significant stimulation was observed 15 seconds after beginning the glyoxylate treatment. The glyoxylate-dependent stimulation was increased by high O2 concentrations and decreased by high CO2 concentrations. Glyoxylate treatment resulted in a 71% inhibition in the rate of CO2 incorporation into glycolate and glycine. Glyoxylate may be stimulating net photosynthesis solely by decreasing photorespiration or it may be increasing the amount of CO2 fixed by …
Mechanism Of Decarboxylation Of Glycine And Glycolate By Isolated Soybean Cells, David J. Oliver
Mechanism Of Decarboxylation Of Glycine And Glycolate By Isolated Soybean Cells, David J. Oliver
David J. Oliver
Isolated soybean leaf mesophyll cells decarboxylated exogenously added [1-14C]glycolate and [1-14C]glycine in the dark. The rate of CO2 release from glycine was inhibited over 90% by isonicotinic acid hydrazide and about 80% by KCN, two inhibitors of the glycine to serine plus CO2 reaction. The release of CO2 from glycolate was inhibited by less than 50% under the same conditions. This indicates that about 50% of the CO2 released from glycolate occurred at a site other than the glycine to serine reaction. The sensitivity of this alternative site of CO2 release to an inhibitor of glycolate oxidase (methyl-2-hydroxy-3-butynoate) but not …
Effect Of Glyoxylate On The Sensitivity Of Net Photosynthesis To Oxygen (The Warburg Effect) In Tobacco, David J. Oliver
Effect Of Glyoxylate On The Sensitivity Of Net Photosynthesis To Oxygen (The Warburg Effect) In Tobacco, David J. Oliver
David J. Oliver
The addition of glyoxylate to tobacco (Nicotiana tabacum) leaf discs inhibited glycolate synthesis and photorespiration and increased net photosynthetic 14CO2 fixation. This inhibition of photorespiration was investigated further by studying the effect of glyoxylate on the stimulation of photosynthesis that occurs when the atmospheric O2 level was decreased from 21 to 3% (the Warburg effect). The Warburg effect is usually ascribed to the increased glycolate synthesis and metabolism that occurs at higher O2 concentrations. Photosynthesis in control discs increased from 59.1 to 94.7 micromoles of CO2 per gram fresh weight per hour (a 60% increase) when the O2 level was …
Inhibition Of Photorespiration And Increase Of Net Photosynthesis In Isolated Maize Bundle Sheath Cells Treated With Glutamate Or Aspartate, David J. Oliver
Inhibition Of Photorespiration And Increase Of Net Photosynthesis In Isolated Maize Bundle Sheath Cells Treated With Glutamate Or Aspartate, David J. Oliver
David J. Oliver
Net photosynthetic 14CO2 fixation by isolated maize (Zea mays) bundle sheath strands was stimulated 20 to 35% by the inclusion of L-glutamate or L-aspartate in the reaction mixture. Maximal stimulation occurred at a 7.5 mM concentration of either amino acid. Since the photosynthetic rate and the glutamate-dependent stimulation in the rate were equally sensitive to a photosynthetic electron transport inhibitor, 3-(p-chlorophenyl)-1,1-dimethylurea, it was concluded that glutamate did not stimulate CO2 fixation by supplying needed NADPH (NADH) through glutamate dehydrogenase. Treatment of the bundle sheath strands with glutamate inhibited glycolate synthesis by 59%. Photorespiration in this tissue, measured as the O2 …
Metabolic Regulation Of Glycolate Synthesis, Photorespiration, And Net Photosynthesis In Tobacco By L-Glutamate, David J. Oliver, Israel Zelitch
Metabolic Regulation Of Glycolate Synthesis, Photorespiration, And Net Photosynthesis In Tobacco By L-Glutamate, David J. Oliver, Israel Zelitch
David J. Oliver
Experiments were undertaken to identify and characterize control mechanisms in tobacco leaf tissue which decrease the relative contribution of photorespiratory CO2 release and thereby increase net photosynthetic CO2 fixation. A number of metabolites were supplied to illuminated leaf discs and their effect on the inhibition of glycolate synthesis was measured. Glycolate accumulation, in the presence of α-hydroxy-2-pyridinemethanesulfonic acid, was inhibited in leaf discs previously floated on 30 mM solutions of either L-glutamate, L-aspartate, phospho-enolpyruvate, or glyoxylate. The effect of glutamate on glycolate synthesis, which was investigated in detail, was concentration- and time-dependent. Glycolate synthesis was inhibited about 40% by treating …
A Simple Carbon Dioxide Injection System For Photosynthetic Studies, David J. Oliver, Stewart I. Cameron, Michael Schaedle
A Simple Carbon Dioxide Injection System For Photosynthetic Studies, David J. Oliver, Stewart I. Cameron, Michael Schaedle
David J. Oliver
A simple carbon dioxide injection system has been developed for the maintenance of CO2 concentrations in semiclosed cuvette systems suitable for photosynthesis and gaseous pollutant studies. The device injects small volumes of pure carbon dioxide into the cuvette in response to a signal from an infrared gas analyzer.