scholarly journals Deiodination of l-thyroxine and its activity on the oxidation in vitro of reduced nicotinamide–adenine dinucleotide by peroxidase plus hydrogen peroxide

1971 ◽  
Vol 125 (3) ◽  
pp. 869-878 ◽  
Author(s):  
Trinidad Jolin ◽  
Gabriella Morreale De Escobar
Keyword(s):  
Nicotinamide Adenine Dinucleotide ◽  
Alternative Explanation ◽  
Diphenyl Ether ◽  
Reaction Medium ◽  
Nadh Oxidation ◽  
Phenolic Ring ◽  
Active Moiety ◽  
Reduced Nicotinamide Adenine Dinucleotide ◽  
Competing Reactions

When l-thyroxine activates the oxidation of NADH by peroxidase+H2O2, little removal of phenolic-ring iodine atoms becomes apparent until most of the NADH has been oxidized, after which it increases markedly. This extensive deiodination is accompanied by loss of the ability of thyroxine to catalyse the oxidation of NADH by peroxidase+H2O2. The slight deiodination observed before the appearance of extensive deiodination is somewhat higher when the effect of thyroxine on NADH oxidation is greater, and lower when thyroxine has exerted a slighter effect. ICN (but not I2 or thyronine) catalyses NADH oxidation, in both the presence and the absence of peroxidase+H2O2: thyroxine+peroxidase+H2O2 are thus comparable with ICN alone in their effects on NADH oxidation. The obvious conclusion from the above observation, namely that the active moiety is the halogen liberated from thyroxine (or ICN) is, however, not directly supported by some of the results obtained by measuring the degree of deiodination of thyroxine in the system. In an attempt to reconcile some apparently contradictory conclusions, it is suggested that, when thyroxine activates oxidation of NADH by peroxidase+H2O2, the diphenyl ether structure is undergoing cyclic deiodination and iodination. This would be accompanied by the maintenance in the reaction medium of an oxidized form of iodine, similar to that liberated by ICN, which would be the actual active moiety, until the NADH concentration becomes so low that the diphenyl ether structure is ruptured oxidatively. An alternative explanation is that thyroxine is oxidized to a form that either oxidizes NADH or loses iodine in competing reactions.

NAD(P)H oxidase–dependent platelet superoxide anion release increases platelet recruitment

Blood ◽  
2002 ◽  
Vol 100 (3) ◽  
pp. 917-924 ◽  
Author(s):  
Florian Krötz ◽  
Hae Young Sohn ◽  
Torsten Gloe ◽  
Stefan Zahler ◽  
Tobias Riexinger ◽  
...  
Keyword(s):  
Nicotinamide Adenine Dinucleotide ◽  
Thrombus Formation ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Human Platelets ◽  
Nicotinamide Adenine ◽  
Irreversible Aggregation ◽  
Reduced Nicotinamide Adenine Dinucleotide ◽  
Specific Peptide

Abstract Platelets, although not phagocytotic, have been suggested to release O2−. Since O2−-producing reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) oxidases can be specifically activated by certain agonists and are found in several nonphagocytotic tissues, we investigated whether such an enzyme is the source of platelet-derived O2−. We further studied which agonists cause platelet O2−release and whether platelet-derived O2− influences thrombus formation in vitro. Collagen, but not adenosine 5′-diphosphate (ADP) or thrombin, increased O2− formation in washed human platelets. This was a reduced nicotinamide adenine dinucleotide (NADH)–dependent process, as shown in platelet lysates. Consistent with a role of a platelet, NAD(P)H oxidase expression of its subunits p47phox and p67phoxand inhibition of platelet O2− formation by diphenylene-iodoniumchloride (DPI) and by the specific peptide-antagonist gp91ds-tat were observed. Whereas platelet-derived O2− did not influence initial aggregation, platelet recruitment to a preformed thrombus following collagen stimulation was significantly attenuated by superoxide dismutase (SOD) or DPI. It was also inhibited when ADP released during aggregation was cleaved by the ectonucleotidase apyrase. ADP in supernatants of collagen-activated platelets was decreased in the presence of SOD, resulting in lower ADP concentrations available for recruitment of further platelets. Exogenous O2−increased ADP- concentrations in supernatants of collagen-stimulated platelets and induced irreversible aggregation when platelets were stimulated with otherwise subthreshold concentrations of ADP. These results strongly suggest that collagen activation induces NAD(P)H oxidase–dependent O2− release in platelets, which in turn enhances availability of released ADP, resulting in increased platelet recruitment.

scholarly journals Transport of reduced nicotinamide–adenine dinucleotide into mitochondria of rat white adipose tissue

1970 ◽  
Vol 116 (2) ◽  
pp. 229-233 ◽  
Author(s):  
B. H. Robinson ◽  
M. L. Halperin
Keyword(s):  
Adipose Tissue ◽  
Rat Liver ◽  
White Adipose Tissue ◽  
Nicotinamide Adenine Dinucleotide ◽  
Aspartate Aminotransferase ◽  
Respiratory Control ◽  
Liver Mitochondria ◽  
Nadh Oxidation ◽  
Rat Liver Mitochondria ◽  
Reduced Nicotinamide Adenine Dinucleotide

Mitochondria from rat white adipose tissue were prepared, exhibiting good respiratory control and P/O ratios. They would not oxidize NADH unless NNN′N′-tetramethyl-p-phenylenediamine was added as a carrier of reducing equivalents. These mitochondria were found to oxidize neither l-glycerol 3-phosphate nor l-glutamate plus l-malate at significant rates. The activity of aspartate aminotransferase in these mitochondria was found to be low compared with that found in rat liver mitochondria. As a consequence of this, the adipose-tissue mitochondria exhibited very low rates of cytoplasmic NADH oxidation in a reconstituted Borst (1962) cycle compared with liver mitochondria.

NAD/NADH: redox state changes on cat brain cortex during stimulation and hypercapnia

1982 ◽  
Vol 243 (4) ◽  
pp. H619-H627 ◽  
Author(s):  
L. Gyulai ◽  
E. Dora ◽  
A. G. Kovach
Keyword(s):  
Nicotinamide Adenine Dinucleotide ◽  
Redox State ◽  
Redox System ◽  
Inhibitory Effect ◽  
Nadh Oxidation ◽  
Nicotinamide Adenine ◽  
Direct Inhibitory Effect ◽  
Anterior Suprasylvian Gyrus ◽  
Reduced Nicotinamide Adenine Dinucleotide

The redox state of the anterior suprasylvian gyrus of cats was measured during electrical stimulation and under hypercapnia on cast immobilized and artificially respirated. The state of the nicotinamide adenine dinucleotide-reduced nicotinamide adenine dinucleotide (NAD/NADH) redox system was monitored by in vivo fluorometry. Hypercapnia was produced by inhalation of 10, 15, and 30% CO2, respectively. Hypercapnic acidosis led to NADH oxidation. The NADH oxidation under 30% CO2 inhalation was significantly larger (-14.9 +/- 2.9%) than that observed under 10% (-6.5 +/- 1.9%) and 15% CO2 (-7.0 +/- 1.6%) inhalation. Under normocapnic conditions, stimulation induced NAD reduction to NADH (5.5 +/- 0.8%). The magnitude of the NAD reductive response to stimulation was unaffected by 10% CO2 inhalation, but it was decreased by 15 and 30% CO2 inhalation. The increased concentration of NADH upon stimulation is interpreted as resulting from an increased rate of substrate mobilization. The cause of the oxidation of the NADH pool of the cell during hypercapnia is partly due to the direct inhibitory effect of CO2 on the carbohydrate metabolism, but the role of other mechanisms cannot be neglected either.

scholarly journals Reduced nicotinamide–adenine dinucleotide–nitrite reductase from Azotobacter chroococcum

1973 ◽  
Vol 133 (4) ◽  
pp. 701-708 ◽  
Author(s):  
J. M. Vega ◽  
M. G. Guerrero ◽  
E. Leadbetter ◽  
M. Losada
Keyword(s):  
Nitrogen Source ◽  
Nitrite Reductase ◽  
Nicotinamide Adenine Dinucleotide ◽  
Culture Media ◽  
Reductase Activity ◽  
Direct Reduction ◽  
Azotobacter Chroococcum ◽  
Soluble Form ◽  
Reduced Nicotinamide Adenine Dinucleotide

1. The assimilatory nitrite reductase of the N2-fixing bacterium Azotobacter chroococcum was prepared in a soluble form from cells grown aerobically with nitrate as the nitrogen source, and some of its properties have been studied. 2. The enzyme is a FAD-dependent metalloprotein (mol.wt. about 67000), which stoicheiometrically catalyses the direct reduction of nitrite to NH3 with NADH as the electron donor. 3. NADH–nitrite reductase can exist in two either active or inactive interconvertible forms. Inactivation in vitro can be achieved by preincubation with NADH. Nitrite can specifically protect the enzyme against this inactivation and reverse the process once it has occurred. 4. A. chroococcum nitrite reductase is an adaptive enzyme whose formation depends on the presence of either nitrate or nitrite in the nutrient solution. 5. Tungstate inhibits growth of the microorganism very efficiently, by competition with molybdate, when nitrate is the nitrogen source, but does not interfere when nitrite or NH3 is substituted for nitrate. The addition of tungstate to the culture media results in the loss of nitrate reductase activity but does not affect nitrite reductase.

scholarly journals Decrease in subunit aggregation of phosphoribosylpyrophosphate synthetase: a mechanism for decreased nucleotide concentrations in pyruvate kinase-deficient human erythrocytes

Blood ◽  
1986 ◽  
Vol 68 (5) ◽  
pp. 1024-1029
Author(s):  
CR Zerez ◽  
NA Lachant ◽  
KR Tanaka
Keyword(s):  
Pyruvate Kinase ◽  
Nicotinamide Adenine Dinucleotide ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Gel Permeation Chromatography ◽  
Metabolic Abnormalities ◽  
Gel Permeation ◽  
Reduced Nicotinamide Adenine Dinucleotide

Pyruvate kinase (PK)-deficient RBCs have several unexplained metabolic abnormalities, such as decreased concentrations of total adenine nucleotides (AMP, ADP, and ATP) and total (oxidized and reduced) nicotinamide adenine dinucleotide (NAD). Because 5-phosphoribosyl-1- pyrophosphate (PRPP) is an intermediate in the synthesis of adenine nucleotides and NAD, we investigated PRPP synthetase (PRPPS), the enzyme responsible for PRPP synthesis. This enzyme is regulated, in part, by changes in its state of subunit aggregation. The proportion of aggregated PRPPS can be altered in vitro by ATP and 2,3- diphosphoglycerate (DPG). Because PK-deficient RBCs have decreased ATP and increased DPG concentrations, we examined the state of subunit aggregation of PRPPS in RBCs from normal and PK-deficient subjects, using gel permeation chromatography. Young normal RBCs have more aggregated PRPPS than do older RBCs. In contrast, due to their decreased ATP and increased DPG concentrations, PK-deficient RBCs contain less aggregated PRPPS than do RBCs of comparable age without PK deficiency. These data suggest that PRPPS should be less active in vivo in PK-deficient RBCs. This may play a key role in mediating the decreases in total adenine nucleotide and total NAD concentrations in these RBCs.

scholarly journals Decrease in subunit aggregation of phosphoribosylpyrophosphate synthetase: a mechanism for decreased nucleotide concentrations in pyruvate kinase-deficient human erythrocytes

Blood ◽  
1986 ◽  
Vol 68 (5) ◽  
pp. 1024-1029 ◽  
Author(s):  
CR Zerez ◽  
NA Lachant ◽  
KR Tanaka
Keyword(s):  
Pyruvate Kinase ◽  
Nicotinamide Adenine Dinucleotide ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Gel Permeation Chromatography ◽  
Metabolic Abnormalities ◽  
Gel Permeation ◽  
Reduced Nicotinamide Adenine Dinucleotide

Abstract Pyruvate kinase (PK)-deficient RBCs have several unexplained metabolic abnormalities, such as decreased concentrations of total adenine nucleotides (AMP, ADP, and ATP) and total (oxidized and reduced) nicotinamide adenine dinucleotide (NAD). Because 5-phosphoribosyl-1- pyrophosphate (PRPP) is an intermediate in the synthesis of adenine nucleotides and NAD, we investigated PRPP synthetase (PRPPS), the enzyme responsible for PRPP synthesis. This enzyme is regulated, in part, by changes in its state of subunit aggregation. The proportion of aggregated PRPPS can be altered in vitro by ATP and 2,3- diphosphoglycerate (DPG). Because PK-deficient RBCs have decreased ATP and increased DPG concentrations, we examined the state of subunit aggregation of PRPPS in RBCs from normal and PK-deficient subjects, using gel permeation chromatography. Young normal RBCs have more aggregated PRPPS than do older RBCs. In contrast, due to their decreased ATP and increased DPG concentrations, PK-deficient RBCs contain less aggregated PRPPS than do RBCs of comparable age without PK deficiency. These data suggest that PRPPS should be less active in vivo in PK-deficient RBCs. This may play a key role in mediating the decreases in total adenine nucleotide and total NAD concentrations in these RBCs.

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