Mechanism of activation of bicarbonate ion by mitochondrial carbamoyl-phosphate synthetase: formation of enzyme-bound adenosine diphosphate from the adenosine triphosphate that yields inorganic phosphate

Biochemistry ◽  
1981 ◽  
Vol 20 (7) ◽  
pp. 1969-1974 ◽  
Author(s):  
Vicente Rubio ◽  
Hubert Greenslade Britton ◽  
Santiago Grisolia ◽  
Brian S. Sproat ◽  
Gordon Lowe
Keyword(s):  
Adenosine Triphosphate ◽  
Inorganic Phosphate ◽  
Adenosine Diphosphate ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate

scholarly journals Product inhibition studies on bovine liver carbamoyl phosphate synthetase

1974 ◽  
Vol 141 (3) ◽  
pp. 817-824 ◽  
Author(s):  
Keith R. F. Elliott ◽  
Keith F. Tipton
Keyword(s):  
Inorganic Phosphate ◽  
Substrate Binding ◽  
Inorganic Ions ◽  
Bovine Liver ◽  
Product Inhibition ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Product Release ◽  
Proposed Model ◽  
Inhibition Studies

A study of the product-inhibition patterns of carbamoyl phosphate synthetase from bovine liver is reported. Inhibition by adenosine, AMP and inorganic ions is also reported. The results are in agreement with the previously proposed model in which the order of substrate binding is ATPMg, followed by HCO3−, ATPMg and NH4+. The order of product release on the basis of the reported results is carbamoyl phosphate, followed by ADPMg, ADPMg and inorganic phosphate.

FACTORS INFLUENCING TETRAZOLE REDUCTION BY REDUCED NICOTINAMIDE–ADENINE DINUCLEOTIDE IN PIGEON-HEART MITOCHONDRIA

1967 ◽  
Vol 45 (2) ◽  
pp. 299-307 ◽  
Author(s):  
C. L. Talesara ◽  
M. C. Blanchaer
Keyword(s):  
Adenosine Triphosphate ◽  
Respiratory Chain ◽  
Nicotinamide Adenine Dinucleotide ◽  
Inorganic Phosphate ◽  
Adenosine Monophosphate ◽  
Adenosine Diphosphate ◽  
Heart Mitochondria ◽  
Nicotinamide Adenine ◽  
Tetrazolium Chloride ◽  
Reduced Nicotinamide Adenine Dinucleotide

The effect of adenosine triphosphate, adenosine diphosphate, adenosine monophosphate and inorganic phosphate on the reduction of 2-(p-iodophenyi)-3-p-nitrophenyl-5-phenyl tetrazolium chloride (INT) to its formazan by reduced nicotinamide-adenine dinucleotide (NADH) was studied in pigeon-heart mitochondria. Formazan production was followed at 540 mμ in 2.2 ml medium containing 0.4–0.5 mg mitochondrial protein, 0.22 M mannitol, 0.067 M sucrose, 0.02 M Tris–chloride, 0.02 mM EDTA, 0.5–3.0 mM INT, and 38 μM NADH at pH 7.2 and 28 °C. By means of the respiratory inhibitors Amytal, rotenone, antimycin A, and cyanide, it was shown that INT diverts electrons from the respiratory chain principally at the flavoprotein level. In contrast to its inhibitory effect on "the O2-linked oxidation of NADH, 10 mM adenosine triphosphate stimulated the reaction rate and formazan yield in the present system. Equimolar inorganic phosphate also increased the initial velocity but adenosine diphosphate and adenosine monophosphate did not. Preliminary kinetic studies suggest that NADH, but not INT, combines with the form of NADH dehydrogenase in the respiratory chain with which adenosine triphosphate reacts.

Harvesting the Light

2018 ◽  
Author(s):  
David R. Dalton
Keyword(s):  
Adenosine Triphosphate ◽  
Nicotinamide Adenine Dinucleotide ◽  
Plant Material ◽  
Inorganic Phosphate ◽  
Adenosine Diphosphate ◽  
High Energy ◽  
Phosphate Ester ◽  
The Sun ◽  
Reduced Forms ◽  
Subsequent Regeneration

Products of reactions are separated from reactants by a barrier or barriers. if this were not so we could not have any reactants—everything would already be products! In order for the grapevine to grow beyond the materials provided in the seed, the rootstock, or the cutting, it is necessary for the reactants obtained from the environment (i.e., nutrients in the soil and air) to be converted to plant material. The energy for this conversion comes from the sun, and it is the chloroplasts that take the light and, using the aforementioned materials, convert it to useful energy in the plant. So, overall, for processes to occur within the plant, a high energy species must be formed and then used. Subsequent regeneration of the high energy species can use more sunlight. The currency of energy is adenosine triphosphate (ATP). When it is used, it is converted to adenosine diphosphate (ADP) and inorganic phosphate (Pi), and in that conversion (or those conversions as more than one can be used to accomplish the same end) the barrier between reactant and product can be overcome (Figure 10.1). Additionally, for moving electrons and protons around where simple solvation (the use of—and interactions with—solvents) will not work, a cofactor (a “factor” that needs to be present in addition to an enzyme to enable the catalyzed reaction to occur) is often needed. These movements of electrons and protons are simply oxidations and reductions (see Appendix 1), and it is common to find oxidation and reduction being effected by using, as cofactors, either the oxidized or reduced forms of the phosphate ester of nicotinamide adenine dinucleotide (NADP+) to/ from (NADPH) and/ or the related conversion of the oxidized/ reduced forms of flavin adenine dinucleotide (FAD)/ (FADH2) (Figure 10.2). A cartoon representation of the chloroplast wall, with the stroma (the colorless fluid filling the chloroplast through which materials move) shown on the top and the lumen of the thylakoid body (where the light- dependent photochemistry occurs) on the bottom is provided in Figure 10.3. The working agents in the membrane are shown.

scholarly journals Nucleotide Transport and Metabolism in Diatoms

Biomolecules ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 761 ◽  
Author(s):  
Ansgar Gruber ◽  
Ilka Haferkamp
Keyword(s):  
Adenosine Triphosphate ◽  
Inorganic Phosphate ◽  
Energy Production ◽  
Higher Plants ◽  
Adenosine Diphosphate ◽  
Intracellular Bacteria ◽  
Nucleotide Synthesis ◽  
Transport Pathways ◽  
Photosynthetic Eukaryotes ◽  
Mitochondrial Energy Production

Plastids, organelles that evolved from cyanobacteria via endosymbiosis in eukaryotes, provide carbohydrates for the formation of biomass and for mitochondrial energy production to the cell. They generate their own energy in the form of the nucleotide adenosine triphosphate (ATP). However, plastids of non-photosynthetic tissues, or during the dark, depend on external supply of ATP. A dedicated antiporter that exchanges ATP against adenosine diphosphate (ADP) plus inorganic phosphate (Pi) takes over this function in most photosynthetic eukaryotes. Additional forms of such nucleotide transporters (NTTs), with deviating activities, are found in intracellular bacteria, and, surprisingly, also in diatoms, a group of algae that acquired their plastids from other eukaryotes via one (or even several) additional endosymbioses compared to algae with primary plastids and higher plants. In this review, we summarize what is known about the nucleotide synthesis and transport pathways in diatom cells, and discuss the evolutionary implications of the presence of the additional NTTs in diatoms, as well as their applications in biotechnology.

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