Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
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Target Concepts:
Gene/Protein
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Query: EC:1.4.1.2 (
glutamate dehydrogenase
)
4,380
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The chain oxidation of glyceraldehyde-3-phosphate dehydrogenase.NADH by perhydroxyl radicals and propagated by molecular oxygen was studied by the xanthine-xanthine oxidase system, 60Co gamma-ray, and pulse radiolysis. The chain length, amount of NADH oxidized per
HO2
generated, increases with increasing acidity of the medium and reaches a value of 73 at pH 5.0. The rate constant for the oxidation of the glyceraldehyde-3-phosphate dehydrogenase.NADH complex by
HO2
was estimated to be 2 X 10(7) M-1 S-1 at ambient temperatures (23-24 degrees C). Rate studies as a function of pH indicate that O2- is unreactive toward the glyceraldehyde-3-phosphate dehydrogenase.NADH complex. Other dehydrogenases (malate dehydrogenase,
glutamate dehydrogenase
, and isocitric dehydrogenase) studied showed no catalytic activity in the oxidation of NADH by
HO2
/O2-.
...
PMID:Glyceraldehyde-3-phosphate dehydrogenase-catalyzed chain oxidation of reduced nicotinamide adenine dinucleotide by perhydroxyl radicals. 718 97
The main pathway for the hepatic oxidation of ethanol to acetaldehyde proceeds via ADH and is associated with the reduction of NAD to NADH; the latter produces a striking redox change with various associated metabolic disorders. NADH also inhibits xanthine dehydrogenase activity, resulting in a shift of purine oxidation to xanthine oxidase, thereby promoting the generation of oxygen-free radical species. NADH also supports microsomal oxidations, including that of ethanol, in part via transhydrogenation to NADPH. In addition to the classic alcohol dehydrogenase pathway, ethanol can also be reduced by an accessory but inducible microsomal ethanoloxidizing system. This induction is associated with proliferation of the endoplasmic reticulum, both in experimental animals and in humans, and is accompanied by increased oxidation of NADPH with resulting H2O2 generation. There is also a concomitant 4- to 10-fold induction of cytochrome P4502E1 (2E1) both in rats and in humans, with hepatic perivenular preponderance. This 2E1 induction contributes to the well-known lipid peroxidation associated with alcoholic liver injury, as demonstrated by increased rates of
superoxide radical
production and lipid peroxidation correlating with the amount of 2E1 in liver microsomal preparations and the inhibition of lipid peroxidation in liver microsomes by antibodies against 2E1 in control and ethanol-fed rats. Indeed, 2E1 is rather "leaky" and its operation results in a significant release of free radicals. In addition, induction of this microsomal system results in enhanced acetaldehyde production, which in turn impairs defense systems against oxidative stress. For instance, it decreases GSH by various mechanisms, including binding to cysteine or by provoking its leakage out of the mitochondria and of the cell. Hepatic GSH depletion after chronic alcohol consumption was shown both in experimental animals and in humans. Alcohol-induced increased GSH turnover was demonstrated indirectly by a rise in alpha-amino-n-butyric acid in rats and baboons and in volunteers given alcohol. The ultimate precursor of cysteine (one of the three amino acids of GSH) is methionine. Methionine, however, must be first activated to S-adenosylmethionine by an enzyme which is depressed by alcoholic liver disease. This block can be bypassed by SAMe administration which restores hepatic SAMe levels and attenuates parameters of ethanol-induced liver injury significantly such as the increase in circulating transaminases, mitochondrial lesions, and leakage of mitochondrial enzymes (e.g.,
glutamic dehydrogenase
) into the bloodstream. SAMe also contributes to the methylation of phosphatidylethanolamine to phosphatidylcholine. The methyltransferase involved is strikingly depressed by alcohol consumption, but this can be corrected, and hepatic phosphatidylcholine levels restored, by the administration of a mixture of polyunsaturated phospholipids (polyenylphosphatidylcholine). In addition, PPC provided total protection against alcohol-induced septal fibrosis and cirrhosis in the baboon and it abolished an associated twofold rise in hepatic F2-isoprostanes, a product of lipid peroxidation. A similar effect was observed in rats given CCl4. Thus, PPC prevented CCl4- and alcohol-induced lipid peroxidation in rats and baboons, respectively, while it attenuated the associated liver injury. Similar studies are ongoing in humans.
...
PMID:Role of oxidative stress and antioxidant therapy in alcoholic and nonalcoholic liver diseases. 889 26
Metal toxicity in crop plants is a matter of scientific concern. Therefore, in recent years efforts have been made to minimize metal toxicity in crop plants. Out of various strategies, priming of seedlings with certain chemicals, like e.g. donors of signaling molecules, nutrients, metabolites or plant hormones has shown encouraging results. However, mechanisms related with the priming-induced mitigation of metal toxicity are still poorly known. Hence, we have tested the potential of 2-oxoglutarate (2-OG) priming in enhancing the arsenate (As
V
) toxicity tolerance in tomato seedlings along with deciphering the probable role of nitric oxide (NO) in accomplishing this task. Arsenate decreased growth, endogenous NO and nitric oxide synthase-like activity but enhanced the accumulation of As, which collectively led to root cell death. Arsenate toxicity also decreased some photosynthetic characteristics (i.e. F
v
/F
m,
qP, F
v
/F
0
and F
m
/F
0
, and total chlorophyll content) but enhanced NPQ. However, priming with 2-OG alleviated the toxic effect of As
V
on growth, endogenous NO, cell death and photosynthesis. Moreover, arsenate inhibited the activities of enzymes of nitrogen metabolism (i.e. nitrate reductase, nitrite reductase, glutamine synthetase and glutamine 2-oxoglutarate aminotransferase) but increased the activity of
glutamate dehydrogenase
and NH
4
+
content.
Superoxide
radicals, hydrogen peroxide, lipid peroxidation, protein oxidation and membrane damage increased upon As
V
exposure, but the antioxidant enzymes (i.e. superoxide dismutase, catalase and glutathione-S-transferase) showed differential responses. Overall, our results showed that 2-OG is capable of alleviating As
V
toxicity in tomato seedlings but the involvement of endogenous NO is probably required.
...
PMID:Priming of tomato seedlings with 2-oxoglutarate induces arsenic toxicity alleviatory responses by involving endogenous nitric oxide. 3265 64
