The FHA cycle is active inside the cell, detoxifying superoxide anion radicals (O2·-), which are mainly generated as a result of so-called 'electron leakage' to triplet oxygen (O2) in photosynthetic, mitochondrial, peroxisomal, and probably other electron transport chains (Ozyigit et al. (deepdyve.com)
Biochemistry bioassays confirmed the involvement of monooxygenase enzyme, carboxylesterase, superoxide dismutase and peroxidase in multi-insecticide resistance mechanism. (preprints.org)
These results, together with previous data, suggest that the network of transcriptional control explains how CATs and other scavenger enzymes such as peroxidase and superoxide dismutase may be coordinately regulated during development, but differentially expressed in response to different stresses for controlling ROS homeostasis. (jipb.net)
Redox3
but if the ascorbate/dehydroascorbate (AA/DHA) ratio is kept high (the redox potential kept reducing) until the unstable dehydro- ascorbate undergoes hydrolysis or can be reduced back to ascorbate, the dehydroascorbate will do no harm. (mall-net.com)
These data show that apoplastic redox-active transition metals are involved in the ascorbate-induced [Ca2+]cyt. (deepdyve.com)
This mechanism may underlie ascorbate release, signalling phenomena, apoplastic redox reactions, iron acquisition, and control the ionic and electrical equilibrium (together with K+ efflux via GORK channels). (deepdyve.com)
Antioxidant2
Clinically, in a disease ameliorated by ascorbate, there is a suppression of symptoms only with very high doses and approximately to that extent which a nonrate-limited,_antioxidant_free_radical_scavenger, might be expected to affect that disease process if all harmful free radicals and highly reactive oxidizing substances were quenched. (mall-net.com)
There are a number of reactive nitrogen oxide species, such as N2O3 and ONOO-, that can alter critical cellular components under high local concentrations of NO. However, NO can also abate the oxidation chemistry mediated by reactive oxygen species such as H2O2 and O2- that occurs at physiological levels of NO. In addition to the antioxidant chemistry, NO protects against cell death mediated by H2O2, alkylhydroperoxides, and xanthine oxidase. (researchgate.net)
Calcium1
Mixtures of mineral ascorbates (calcium, magnesium, potassium, zinc, and sometimes sodium) are used in certain circumstances to increase bowel tolerance for even more clinical effectiveness but do not clearly demonstrate the increasing bowel tolerance phenomenon being discussed here. (mall-net.com)
Environmental1
Our results reveal that CAT1 is an important player in the removal of H2O2 generated under various environmental stresses. (jipb.net)
High2
Since even at very high doses, ascorbate is virtually nontoxic, it may be given in the enormous doses necessary to quench almost all unwanted free radicals and oxidants. (mall-net.com)
Low or moderate doses (doses substantially below bowel tolerance) usually had no noticeable immediate beneficial effects, but high doses (doses just below the amount that would produce diarrhea in a patient tolerant to ascorbate) would have the effect of markedly suppressing symptoms as the high dose levels were reached. (mall-net.com)
Free1
elevation, while cation channel blockers, free radical scavengers, low extracellular [Ca2+], transition metal chelators, and removal of the cell wall inhibit this reaction. (deepdyve.com)
Effective1
It is as if a threshold were reached at which point the ascorbate becomes very effective. (mall-net.com)
Cell1
Exogenous ascorbate also induces a moderate increase in programmed cell death symptoms in intact roots, but it does not activate Ca2+ influx currents in patch-clamped root protoplasts. (deepdyve.com)
Catalase8
Catalase-peroxidases, also called KatGs, have raised considerable interest due to their role in the activation of isoniazid, an anti-tubercular pro-drug for Mycobacterium tuberculosis. (auburn.edu)
At this point, the reduction of compound I to the ferric state differs for both the catalase and peroxidase activities. (auburn.edu)
To complete the catalase reaction, compound I returns to the ferric state by oxidation of another H2O2 to form O2 and H2O. (auburn.edu)
Catalase activity is optimal near neutral pH (i.e., pH ~ 7.5), whereas peroxidase activity is optimal under acidic conditions (i.e., pH ~ 4.5) and requires an exogenous electron donor. (auburn.edu)
Conversely, catalase activity can sustain high concentrations of H2O2 without the enzyme inactivation. (auburn.edu)
Clearly, conditions which favor the peroxidase activity do not coincide with those that favor the catalase activity. (auburn.edu)
intermediate dominated during electron donor-stimulated catalase activity of MtKatG, and this intermediate converted directly to the ferric state upon depletion of H2O2. (auburn.edu)
Clearly, the catalase mechanism and the interrelationship between the catalase and peroxidase functions of KatG are much more complex than has been previously appreciated, and pH plays an important factor in both activities. (auburn.edu)
Oxidation1
The initial step for both catalytic processes is the heterolytic reduction of H2O2 to H2O, giving rise to a two-electron oxidation of the ferric enzyme to a ferryl-porphyrin π cation radical intermediate, compound I (i.e. (auburn.edu)
Equivalent2
This is far less than the amount expected for normal peroxidatic turnover where two equivalents of oxidized donor is anticipated for every equivalent of H2O2 consumed. (auburn.edu)
Reaction of chromium(VI) with one equivalent of ascorbate was studied by electron paramagnetic resonance spectroscopy in the presence of 0.10 M 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) at room temperature in 0.10 M (N-[2-hydroxyethyl]piperazine-N'-[2-ethanesulfonic acid]) (HEPES) and 0.05 M tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) buffers (pH 7.0 room temperature). (nih.gov)
Electron1
The ability of one activity to dominate over the other depends on several factors including: pH, the concentration of H2O2, and the availability of an appropriate exogenous electron donor. (auburn.edu)
Reaction1
However, the peroxidase reaction is completed by the subsequent reduction of compound I to compound II (i.e. (auburn.edu)
Mechanisms1
As the name suggests, they catalyze the decomposition of H2O2 by catalatic and peroxidatic mechanisms using a single active site. (auburn.edu)
Reduction1
Chromium(VI) reduction by ascorbate: role of reactive intermediates in DNA damage in vitro. (nih.gov)
Activity3
More so, peroxidase activity is favorable at low H2O2 concentrations. (auburn.edu)
The stimulatory effect was most prominent under conditions favorable to peroxidase activity (i.e., acidic pH and low H2O2 concentrations). (auburn.edu)
Loss of PLA2 may affect the levels of specific lipids altering lipid signaling pathways, while loss of peroxidase activity could induce redox changes at critical sensitive cysteine residues in key proteins. (biomed.news)