Snyrychová Iva, Pospísil Pavel, Naus Jan
Laboratory of Biophysics, Department of Experimental Physics, Faculty of Science, Palacký University, tr. Svobody 26, 771 46 Olomouc, Czech Republic.
Photosynth Res. 2006 Jun;88(3):323-9. doi: 10.1007/s11120-006-9061-0. Epub 2006 Jun 6.
The effect of metal chelators (EDTA, DTPA and Desferal) on the metal-catalyzed decomposition of hydrogen peroxide was studied using EPR spin-trapping spectroscopy. The formation of hydroxyl radicals (OH*) in both chemical (Fenton reaction) and biological (thylakoids) systems was stimulated by EDTA. DTPA promoted the generation of OH* in the presence of strong reducing agents, whereas in their absence it acted as an antioxidant. Desferal suppressed OH* production even in the presence of reductants. In our study, we have shown that metal chelators can both stimulate and suppress the formation of OH*, depending on the experimental conditions. In illuminated thylakoids we have observed prooxidant effect of EDTA and DTPA, possibly due to their reduction by some component of the electron transport chain. According to our results, metal chelators should not be used as antioxidants without prior testing of their effect in given samples.
利用电子顺磁共振自旋捕集光谱法研究了金属螯合剂（乙二胺四乙酸、二乙烯三胺五乙酸和去铁胺）对金属催化的过氧化氢分解的影响。在化学体系（芬顿反应）和生物体系（类囊体）中，乙二胺四乙酸均能促进羟基自由基（OH*）的形成。在存在强还原剂的情况下，二乙烯三胺五乙酸促进OH的生成，而在不存在强还原剂的情况下，它起到抗氧化剂的作用。即使在存在还原剂的情况下，去铁胺也能抑制OH的产生。在我们的研究中，我们已经表明，根据实验条件，金属螯合剂既能促进也能抑制OH*的形成。在光照的类囊体中，我们观察到乙二胺四乙酸和二乙烯三胺五乙酸的促氧化作用，这可能是由于它们被电子传递链的某些成分还原所致。根据我们的结果，在未事先测试其在给定样品中的效果之前，金属螯合剂不应用作抗氧化剂。
