Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 11, 783 71, Olomouc, Czech Republic.
J Bioenerg Biomembr. 2013 Dec;45(6):551-9. doi: 10.1007/s10863-013-9523-y. Epub 2013 Aug 11.
In this study, electron paramagnetic resonance spin-trapping spectroscopy was used to study the light-induced production of superoxide anion (O2 (•-)) and carbon-centered (R(•)) radicals by Photosystem II (PSII). It is evidenced here that exposure of PSII membranes to high light (2,000 μmol photons m(-2) s(-1)) or heat (47 °C) treatments prior to the illumination suppressed O2 (•-) production, while R(•) was formed. Formation of R(•) in the both high light- and heat-treated PSII membranes was enhanced by DCMU. Removal of molecular oxygen by glucose/glucose oxidase/catalase system and O2 (•-) scavenging by exogenous superoxide dismutase completely suppressed carbon-centered radical formation. It is proposed here that the oxidation of polyunsaturated fatty acids and amino acids by O2 (•-) on the electron acceptor side of PSII results in the formation of R(•), known to initiate a cascade reaction leading to the lipid peroxidation and protein degradation, respectively.
在这项研究中，电子顺磁共振自旋捕获光谱学被用于研究光诱导的光合系统 II（PSII）中过氧阴离子（O2（•-））和碳中心（R（•））自由基的产生。这里有证据表明，在光照之前，将 PSII 膜暴露于强光（2000 μmol 光子 m(-2) s(-1)）或热（47°C）处理会抑制 O2（•-）的产生，而 R（•）则形成。DCMU 增强了在强光和热处理的 PSII 膜中 R（•）的形成。通过葡萄糖/葡萄糖氧化酶/过氧化氢酶系统去除分子氧和通过外源超氧化物歧化酶清除 O2（•-）完全抑制了碳中心自由基的形成。这里提出，O2（•-）在 PSII 的电子受体侧对多不饱和脂肪酸和氨基酸的氧化导致 R（•）的形成，已知 R（•）引发级联反应，分别导致脂质过氧化和蛋白质降解。
