Carbon-2 proton exchange at histidine-41 in bovine erythrocyte superoxide dismutase.
Ontology highlight
ABSTRACT:
SUBMITTER: Cass AE
PROVIDER: S-EPMC1164943 | biostudies-other | 1977 Sep
REPOSITORIES: biostudies-other
Similar Datasets
Project description:The binding of zinc(II) ions to apo-(bovine erythrocytes superoxide dismutase) was studied by 1H n.m.r. spectroscopy. Two zinc(II) ions bind to each subunit of the apoenzyme, and the first has a binding constant at least an order of magnitude larger than the second. The nature of the spectral changes that occur on binding the first zinc(II) ion are interpreted in terms of a change in the structure of the protein around the active site to one very similar to that of the holoenzyme, thus pre-forming the second zinc(II) binding site. The binding of the second zinc(II) ion effects changes in the environment of only those residues involved in its co-ordination.
| S-EPMC1186397 | biostudies-other
Project description:RationaleOxidant stress may increase the severity of respiratory distress syndrome (RDS) after premature birth by altering vasoreactivity and increasing lung edema, but the acute effects of superoxide dismutase (SOD) treatment on gas exchange, lung compliance (CL), and pulmonary vascular resistance in premature animals with RDS are unknown.ObjectiveWe studied the effects of intratracheal recombinant human SOD treatment (rhSOD) on gas exchange, CL, and pulmonary hemodynamics in 46 premature lambs with RDS.MethodsAfter C-section delivery, lambs were randomly assigned to treatment with SOD (2.5-10 mg/kg) with or without inhaled nitric oxide (iNO, 5 ppm), and mechanically ventilated for 4 hours. At the end of the study, pressure-volume curves and wet-dry lung weights were measured to assess CL and edema, respectively.Main resultsDespite an initial rise in Pa(O(2)), Pa(O(2)) in control animals progressively declined over the 4-hour treatment period (Pa(O(2)) = 25.0 +/- 7.5 mm Hg at 4 hours). In comparison with control animals, early treatment with SOD at 5 and 10 mg/kg improved Pa(O(2)) at 4 hours (167 +/- 44 and 269 +/- 33 mm Hg, respectively; p < 0.05 vs. control), but did not decrease lung edema or improve CL. In contrast, late treatment with SOD did not improve Pa(O(2)). Treatment with iNO increased Pa(O(2)) (196 +/- 22 vs. 25 +/- 8 mm Hg, control animals; p < 0.01), but the response to iNO was not augmented by combined therapy (SOD + iNO). After 4 hours of ventilation with FI(O(2)) = 1.00, rhSOD treatment lowered pulmonary vascular resistance compared with control animals.ConclusionsEarly intratracheal rhSOD treatment improves oxygenation in premature lambs with RDS and prevents the development of pulmonary hypertension.
| S-EPMC2718553 | biostudies-literature
Project description:In eukaryotes, the Cu/Zn containing superoxide dismutase (SOD1) plays a critical role in oxidative stress protection as well as in signaling. We recently demonstrated a function for Saccharomyces cerevisiae Sod1p in signaling through CK1? casein kinases and identified the essential proton ATPase Pma1p as one likely target. The connection between Sod1p and Pma1p was explored further by testing the impact of sod1? mutations on cells expressing mutant alleles of Pma1p that alter activity and/or post-translational regulation of this ATPase. We report here that sod1? mutations are lethal when combined with the T912D allele of Pma1p in the C-terminal regulatory domain. This "synthetic lethality" was reversed by intragenic suppressor mutations in Pma1p, including an A906G substitution that lies within the C-terminal regulatory domain and hyper-activates Pma1p. Surprisingly the effect of sod1? mutations on Pma1-T912D is not mediated through the Sod1p signaling pathway involving the CK1? casein kinases. Rather, Sod1p sustains life of cells expressing Pma1-T912D through oxidative stress protection. The synthetic lethality of sod1? Pma1-T912D cells is suppressed by growing cells under low oxygen conditions or by treatments with manganese-based antioxidants. We now propose a model in which Sod1p maximizes Pma1p activity in two ways: one involving signaling through CK1? casein kinases and an independent role for Sod1p in oxidative stress protection.
| S-EPMC4458189 | biostudies-literature
Project description:Some commercial samples of bovine catalase contain superoxide dismutase activity. Therefore the inhibition of a reaction on the addition of a catalase preparation need not necessarily mean that H(2)O(2) is responsible for the reaction.
| S-EPMC1165834 | biostudies-other
Project description:Human manganese superoxide dismutase is a critical oxidoreductase found in the mitochondrial matrix. Concerted proton and electron transfers are used by the enzyme to rid the mitochondria of O2•-. The mechanisms of concerted transfer enzymes are typically unknown due to the difficulties in detecting the protonation states of specific residues and solvent molecules at particular redox states. Here, neutron diffraction of two redox-controlled manganese superoxide dismutase crystals reveal the all-atom structures of Mn3+ and Mn2+ enzyme forms. The structures deliver direct data on protonation changes between oxidation states of the metal. Observations include glutamine deprotonation, the involvement of tyrosine and histidine with altered pKas, and four unusual strong-short hydrogen bonds, including a low barrier hydrogen bond. We report a concerted proton and electron transfer mechanism for human manganese superoxide dismutase from the direct visualization of active site protons in Mn3+ and Mn2+ redox states.
| S-EPMC8024262 | biostudies-literature
Project description:N.m.r. and e.p.r. were used to measure the oxidation state of copper in Cu,Zn superoxide dismutase treated with reducing agents such as NaBH4, K4Fe(CN)6, Na2S2O4 and H2O2. The activity and the electrophoretic pattern of the treated enzyme were also studied. On the basis of the reducing ability and of the absence of inactivating effects, NaBH4 was the most suitable reducer of those tested. Some characteristics of the reduction of superoxide dismutase by NaBH4 were further investigated. The results obtained indicate that NaBH4 can be used to prepare, in a few minutes, solutions of completely reduced enzyme without any apparent change of the activity and of the structure.
| S-EPMC1145153 | biostudies-other
Project description:Compelling evidence support an involvement of oxidative stress and intestinal inflammation as early events in the predisposition and development of obesity and its related comorbidities. Here we show that deficiency of the major mitochondrial antioxidant enzyme superoxide dismutase 2 (SOD2) in the gastrointestinal tract drives spontaneous obesity. Intestinal epithelium-specific Sod2 ablation in mice induced adiposity, inflammation and insulin resistance via phospholipase A2 (PLA2) activation and increased synthesis of omega-6 polyunsaturated fatty acid arachidonic acid. Remarkably, this obese and hyperinsulinemic phenotype was rescued when fed an essential fatty acid deficient diet, which abrogates de novo biosynthesis of arachidonic acid. Data from clinical samples revealed that the negative correlation between intestinal SOD2 mRNA levels and obesity features, such as body mass index and omega-6/omega-3 fatty acid ratio, appears to be conserved between mice and humans. Collectively, our findings suggest a role of intestinal SOD2 levels, PLA2 activity and arachidonic acid in obesity presenting new potential targets of therapeutic interest in the context of this metabolic disorder.
2021-12-31 | GSE158237 | GEO
Project description:The antral follicle constitutes a complex and regulated ovarian microenvironment that influences oocyte quality. Oxidative stress is a cellular state that may play a role during folliculogenesis and oogenesis, although direct supporting evidence is currently lacking. We thus evaluated the expression of the three isoforms (SOD1, SOD2, and SOD3) of the enzymatic antioxidant superoxide dismutase in all the cellular (granulosa cells, cumulus cells, and oocytes) and extracellular (follicular fluid) compartments of the follicle. Comparisons were made in bovine ovaries across progressive stages of antral follicular development. Follicular fluid possessed increased amounts of SOD1, SOD2, and SOD3 in small antral follicles when compared with large antral follicles; concomitantly, total SOD activity was highest in follicular fluids from smaller diameter follicles. SOD1, SOD2, and SOD3 proteins were expressed in granulosa cells without any fluctuations in follicle sizes. All three SOD isoforms were present, but were distributed differently in oocytes from small, medium, or large antral follicles. Cumulus cells expressed high levels of SOD3, some SOD2, but no detectable SOD1. Our studies provide a temporal and spatial expression profile of the three SOD isoforms in the different compartments of the developing bovine antral follicles. These results lay the ground for future investigations into the potential regulation and roles of antioxidants during folliculogenesis and oogenesis.
| S-EPMC3244472 | biostudies-literature
Project description:On the basis of the thermal stability of erythrocuprein (Cu2Zn2-superoxide dismutase) a rapid preparation technique was devised and successfully employed to isolate this protein. Partial heat-deterioration of the haemolysate and subsequent chromatography of the supernatant on DEAE-Sephacel and Sephadex G-75 yielded an electrophoretically homogeneous protein within a few days. The physicochemical properties and biochemical function were identical with those reported for Cu2Zn2-superoxide dismutases prepared by established methods.
| S-EPMC1144073 | biostudies-other
Project description:The acid-activated proton channel formed by the influenza M2 protein is important for the life cycle of the virus. A single histidine, His37, in the M2 transmembrane domain (M2TM) is responsible for pH activation and proton selectivity of the channel. Recent studies suggested three models for how His37 mediates proton transport: a shuttle mechanism involving His37 protonation and deprotonation, a H-bonded imidazole-imidazolium dimer model, and a transporter model involving large protein conformational changes in synchrony with proton conduction. Using magic-angle-spinning (MAS) solid-state NMR spectroscopy, we examined the proton exchange and backbone conformational dynamics of M2TM in a virus-envelope-mimetic membrane. At physiological temperature and pH, (15)N NMR spectra show fast exchange of the imidazole (15)N between protonated and unprotonated states. To quantify the proton exchange rates, we measured the (15)N T(2) relaxation times and simulated them for chemical-shift exchange and fluctuating N-H dipolar fields under (1)H decoupling and MAS. The exchange rate is 4.5 × 10(5) s(-1) for N?1 and 1.0 × 10(5) s(-1) for N?2, which are approximately synchronized with the recently reported imidazole reorientation. Binding of the antiviral drug amantadine suppressed both proton exchange and ring motion, thus interfering with the proton transfer mechanism. By measuring the relative concentrations of neutral and cationic His as a function of pH, we determined the four pK(a) values of the His37 tetrad in the viral membrane. Fitting the proton current curve using the charge-state populations from these pK(a)'s, we obtained the relative conductance of the five charge states, which showed that the +3 channel has the highest time-averaged unitary conductance. At physiologically relevant pH, 2D correlation spectra indicated that the neutral and cationic histidines do not have close contacts, ruling out the H-bonded dimer model. Moreover, a narrowly distributed nonideal helical structure coexists with a broadly distributed ideal helical conformation without interchange on the sub-10 ms time scale, thus excluding the transporter model in the viral membrane. These data support the shuttle mechanism of proton conduction, whose essential steps involve His-water proton exchange facilitated by imidazole ring reorientations.
| S-EPMC3288706 | biostudies-literature