Photosystem II (PSII) is an intrinsic membrane protein complex that functions as a light-driven water:plastoquinone oxidoreductase in oxygenic photosynthesis. Electron transport in PSII is associated with formation of reactive oxygen species (ROS) responsible for oxidative modifications of PSII proteins. In this study, oxidative modifications of the D1 and D2 proteins by the superoxide anion (O2•-) and the hydroxyl (HO•) radicals were studied in WT and a tocopherol cyclase (vte1) mutant, which is deficient in the lipid-soluble antioxidant α-tocopherol. In the absence of this antioxidant, high-resolution tandem mass spectrometry was used to identify oxidation of D1:130E to hydroxyglutamic acid by O2•- at the PheoD1 site. Additionally, D1:246Y was modified to either tyrosine hydroperoxide or dihydroxyphenylalanine by O2•- and HO•, respectively, in the vicinity of the nonheme iron. We propose that α-tocopherol is localized near PheoD1 and the nonheme iron, with its chromanol head exposed to the lipid-water interface. This helps to prevent oxidative modification of the amino acid's hydrogen that is bonded to PheoD1 and the nonheme iron (via bicarbonate), and thus protects electron transport in PSII from ROS damage.

• MeSH
• alfa-tokoferol chemie   metabolismus   MeSH
• aminokyseliny chemie   metabolismus   MeSH
• Arabidopsis enzymologie   genetika   účinky záření   MeSH
• fotosyntéza fyziologie   účinky záření   MeSH
• fotosystém II - proteinový komplex chemie   genetika   metabolismus   MeSH
• hydroxylový radikál chemie   metabolismus   MeSH
• interakční proteinové domény a motivy MeSH
• intramolekulární transferasy chemie   genetika   metabolismus   MeSH
• konformace proteinů, alfa-helix MeSH
• konformace proteinů, beta-řetězec MeSH
• kyslík chemie   metabolismus   MeSH
• molekulární modely MeSH
• mutace MeSH
• oxidace-redukce MeSH
• superoxidy chemie   metabolismus   MeSH
• světlo MeSH
• termodynamika MeSH
• Thermosynechococcus enzymologie   genetika   účinky záření   MeSH
• tylakoidy enzymologie   genetika   účinky záření   MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• železo chemie   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

Tocopherols, lipid-soluble antioxidants play a crucial role in the antioxidant defense system in higher plants. The antioxidant function of α-tocopherol has been widely studied; however, experimental data on the formation of its oxidation products is missing. In this study, we attempt to provide spectroscopic evidence on the detection of oxidation products of α-tocopherol formed by its interaction with singlet oxygen and lipid peroxyl radical. Singlet oxygen was formed using photosensitizer rose bengal and thylakoid membranes isolated from Arabidopsis thaliana. Singlet oxygen reacts with polyunsaturated fatty acid forming lipid hydroperoxide which is oxidized by ferric iron to lipid peroxyl radical. The addition of singlet oxygen to double bond carbon on the chromanol head of α-tocopherol forms α-tocopherol hydroperoxide detected using fluorescent probe swallow-tailed perylene derivative. The decomposition of α-tocopherol hydroperoxide forms α-tocopherol quinone. The hydrogen abstraction from α-tocopherol by lipid peroxyl radical forms α-tocopheroxyl radical detected by electron paramagnetic resonance. Quantification of lipid and protein hydroperoxide from the wild type and tocopherol deficient (vte1) mutant Arabidopsis leaves using a colorimetric ferrous oxidation-xylenol orange assay reveals that α-tocopherol prevents formation of both lipid and protein hydroperoxides at high light. Identification of oxidation products of α-tocopherol might contribute to a better understanding of the protective role of α-tocopherol in the prevention of oxidative damage in higher plants at high light.

• MeSH
• alfa-tokoferol chemie   metabolismus   MeSH
• antioxidancia chemie   metabolismus   MeSH
• Arabidopsis genetika   růst a vývoj   metabolismus   účinky záření   MeSH
• lipidové peroxidy chemie   metabolismus   MeSH
• oxidace-redukce MeSH
• oxidační stres * MeSH
• peroxid vodíku chemie   metabolismus   MeSH
• singletový kyslík chemie   metabolismus   MeSH
• světlo škodlivé účinky   MeSH
• vitamin E chemie   metabolismus   MeSH
• volné radikály chemie   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

We compared the effect of alpha-tocopheryl succinate (TOS) on succinate-dependent respiration in rat liver mitochondria, homogenate and permeabilized hepatocytes in both a coupled and uncoupled state. In isolated mitochondria, a significant inhibitory effect was observed at a concentration of 5 microM, in liver homogenate at 25 microM and in permeabilized hepatocytes at 50 microM. The inhibitory effect of TOS on succinate respiration in an uncoupled state was less pronounced than in a coupled state in all the experimental models tested. When the concentration dependence of the TOS inhibitory effect was tested, the most sensitive in both states were isolated mitochondria; the most resistant were permeabilized hepatocytes.

• MeSH
• alfa-tokoferol metabolismus   farmakologie   MeSH
• buněčná membrána metabolismus   MeSH
• buněčné dýchání účinky léků   MeSH
• časové faktory MeSH
• energetický metabolismus účinky léků   MeSH
• hepatocyty účinky léků   metabolismus   MeSH
• jaterní mitochondrie účinky léků   metabolismus   MeSH
• karbonylkyanid-p-trifluormethoxyfenylhydrazon farmakologie   MeSH
• oxidativní fosforylace účinky léků   MeSH
• permeabilita buněčné membrány MeSH
• potkani Wistar MeSH
• respirační komplex II metabolismus   MeSH
• rozpřahující látky farmakologie   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

Oxidative stress has been proposed as one of the potential causes for infertility in men. Retinol and α-tocopherol have an important role in the spermatozoa defences against oxidative stress. A method is described here for the simultaneous determination of retinol and α-tocopherol in human seminal plasma with a suitable sample preparation procedure to prevent retinol and α-tocopherol degradation. After adequate sample preparation, the samples were determined by reversed-phase column chromatography with UV detection. The analytical performance of this method was satisfactory. The intra-assay and inter-assay coefficients of variation were below 10%. The recoveries were as follows: 90.7% (CV 8.1%) for retinol and 98.2% (CV 4.8%) for α-tocopherol. No significant differences in both retinol and α-tocopherol concentration between the smokers and nonsmokers (15 ± 7 nm and 1.86 ± 0.29 μm versus 15 ± 6 nm and 1.93 ± 0.45 μm) were found. A selective high-performance liquid chromatography method for the determination of retinol and α-tocopherol in human seminal plasma was developed.

• MeSH
• alfa-tokoferol metabolismus   MeSH
• chromatografie s reverzní fází MeSH
• dospělí MeSH
• kouření metabolismus   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• reprodukovatelnost výsledků MeSH
• spektrofotometrie ultrafialová metody   MeSH
• sperma metabolismus   MeSH
• studie případů a kontrol MeSH
• vitamin A metabolismus   MeSH
• vysokoúčinná kapalinová chromatografie metody   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

All living organisms emit spontaneous ultraweak photon emission as a result of cellular metabolic processes. In this study, the involvement of reactive oxygen species (ROS) formed as the byproduct of oxidative metabolic processes in spontaneous ultraweak photon emission was studied in human hand skin. The effect of molecular oxygen and ROS scavengers on spontaneous ultraweak photon emission from human skin was monitored using a highly sensitive photomultiplier tube and charged coupled device camera. When spontaneous ultraweak photon emission was measured under anaerobic conditions, the photon emission was decreased, whereas under hyperaerobic condition the enhancement in photon emission was observed. Spontaneous ultraweak photon emission measured after topical application of glutathione, α-tocopherol, ascorbate, and coenzyme Q10 was observed to be decreased. These results reveal that ROS formed during the cellular metabolic processes in the epidermal cells play a significant role in the spontaneous ultraweak photon emission. It is proposed that spontaneous ultraweak photon emission can be used as a noninvasive tool for the temporal and spatial monitoring of the oxidative metabolic processes and intrinsic antioxidant system in human skin.

• MeSH
• alfa-tokoferol metabolismus   MeSH
• dospělí MeSH
• fotografování MeSH
• fotony MeSH
• fyziologie kůže účinky léků   MeSH
• glutathion metabolismus   MeSH
• kůže chemie   účinky léků   metabolismus   MeSH
• kyselina askorbová metabolismus   MeSH
• kyslík metabolismus   MeSH
• lidé MeSH
• ruka MeSH
• scavengery volných radikálů farmakologie   MeSH
• spektrofotometrie přístrojové vybavení   metody   MeSH
• ubichinon analogy a deriváty   metabolismus   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• alfa-tokoferol aplikace a dávkování   farmakologie   metabolismus   MeSH
• hodnocení stavu výživy MeSH
• kardiovaskulární nemoci metabolismus   prevence a kontrola   MeSH
• lidé MeSH
• nedostatek vitaminu E metabolismus   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH

Contrary to clinical trials, experimental studies revealed that diabetes mellitus (DM) may initiate, besides increased myocardial vulnerability to ischemia-reperfusion injury (I/R) and pro/antioxidant dysbalance, development of adaptation leading to an enhanced tolerance to I/R. The aims were to characterize 1) susceptibility to ischemia-induced ventricular arrhythmias in the diabetic rat heart 2) its response to antioxidant N-acetylcysteine (NAC) and a NOS inhibitor L-NAME, and 3) the effect of DM on endogenous antioxidant systems. Seven days after streptozotocin injection (65 mg/kg, i.p.), Langendorff-perfused control (C) and DM hearts were subjected to 30-min occlusion of the LAD coronary artery with or without prior 15-min treatment with L-NAME (100 microM) or NAC (4 mM). Total number of ventricular premature beats (VPB), as well the total duration of ventricular tachycardia (VT) were reduced in the DM group (from 533+/-58 and 37.9+/-10.2 s to 224.3+/-52.6 and 19+/-13.5 s; P<0.05). In contrast to the antiarrhythmic effects of L-NAME and NAC in controls group (VPB 290+/-56 and 74+/-36, respectively; P<0.01 vs. control hearts), application of both drugs in the diabetics did not modify arrhythmogenesis (L-NAME: VPB 345+/-136, VT 25+/-13 s; NAC: VPB 207+/-50, VT 12+/-3.9 s; P>0.05 vs non-treated diabetic hearts). Diabetic state was associated with significantly elevated levels of CoQ10 and CoQ9 (19.6+/-0.8 and 217.3+/-9.5 vs. 17.4+/- 0.5 and 185.0+/-5.0 nmol/g, respectively, in controls; P<0.05), as well as alpha-tocopherol (38.6+/-0.7 vs. 31.5+/-2.1 nmol/g in controls; P<0.01) in the myocardial tissue. It is concluded that early period of DM is associated with enhanced resistance to ischemia-induced arrhythmias. Diabetes mellitus might induce adaptive processes in the myocardium leading to lower susceptibility to antioxidant and L-NAME treatment.

• MeSH
• acetylcystein farmakologie   MeSH
• alfa-tokoferol metabolismus   MeSH
• antioxidancia farmakologie   MeSH
• experimentální diabetes mellitus komplikace   farmakoterapie   enzymologie   patofyziologie   MeSH
• funkce levé komory srdeční MeSH
• fyziologická adaptace MeSH
• inhibitory enzymů farmakologie   MeSH
• ischemická choroba srdeční komplikace   farmakoterapie   enzymologie   patofyziologie   MeSH
• komorová tachykardie enzymologie   etiologie   patofyziologie   prevence a kontrola   MeSH
• krysa rodu rattus MeSH
• myokard enzymologie   MeSH
• NG-nitroargininmethylester farmakologie   MeSH
• potkani Wistar MeSH
• synthasa oxidu dusnatého antagonisté a inhibitory   metabolismus   MeSH
• ubichinon analogy a deriváty   metabolismus   MeSH
• upregulace MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• alfa-tokoferol farmakologie   metabolismus   MeSH
• antioxidancia farmakologie   metabolismus   MeSH
• aorta MeSH
• arterioskleróza genetika   metabolismus   MeSH
• finanční podpora výzkumu jako téma MeSH
• gama-tokoferol farmakologie   metabolismus   MeSH
• lidé MeSH
• myokard metabolismus   MeSH
• oxidační stres MeSH
• Check Tag
• lidé MeSH

• MeSH
• alfa-tokoferol krev   metabolismus   terapeutické užití   MeSH
• ateroskleróza krev   metabolismus   MeSH
• fagocyty * fyziologie   patologie   účinky léků   MeSH
• hyperlipoproteinemie * krev   metabolismus   MeSH
• kyselina askorbová krev   metabolismus   terapeutické užití   MeSH
• lidé MeSH
• lipidové peroxidy krev   metabolismus   MeSH
• luminiscence MeSH
• poruchy metabolismu lipidů krev   metabolismus   MeSH
• reaktivní formy kyslíku * krev   metabolismus   MeSH
• statistika jako téma MeSH
• studie případů a kontrol MeSH
• Check Tag
• lidé MeSH

• MeSH
• alfa-tokoferol analýza   metabolismus   účinky záření   MeSH
• hematopoéza MeSH