Advanced Glycation Endproducts Induce Photocrosslinking and Oxidation of Bovine Lens Proteins Through Type-I Mechanism
Advanced Glycation Endproducts Induce Photocrosslinking and Oxidation of Bovine Lens Proteins Through Type-I Mechanism
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DOI：
10.1111/j.1751-1097.2008.00415.x
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发表时间：
2009-01-01
影响因子：
3.3
通讯作者：
Silva, Eduardo
中科院分区：
文献类型：
--
作者：
Fuentealba, Denis;Friguet, Bertrand;Silva, Eduardo
晚期糖基化终产物（AGEs）被认为是能够介导眼透镜老化过程中光损伤的光敏剂。在目前的工作中，我们调查的光交联和氧化的牛透镜蛋白敏化AGEs，特别是在低氧条件下。使用不同的氧浓度和特定的添加剂进行了机理研究，目的是抑制或增强I型或II型光过程。在铁氰化物和D2 O的存在下，在5%、20%和100%O-2下测定Trp分解的量子产率，以阐明AGEs的作用机制。I型机理被证明是AGE敏化Trp在低氧浓度下分解的最有效途径。观察到由于I型相互作用导致的透镜蛋白和晶状体蛋白组分的光交联。研究了氧气浓度和添加剂对反应的影响。结果表明，I型机理和氧介导的反应都有助于蛋白质交联。用Oxyblot技术检测蛋白质光氧化引起的羰基形成。在辐照过程中检测到高水平过氧化氢的产生，主要归因于I型反应。结果支持AGEs在透镜中发现的低氧浓度下优先作为I型敏化剂，并且能够诱导蛋白质交联、氧化和过氧化物形成。
Advanced glycation endproducts (AGEs) have been suggested as photosensitizers that are capable of mediating eye lens photo-damage during aging. In the present work, we investigate the photo-crosslinking and oxidation of bovine lens proteins sensitized by AGEs, with special regard to low oxygen conditions. A mechanistic study was conducted using different oxygen concentrations and specific additives with the aim either to scavenge or enhance Type-I or Type-II photoprocesses. Quantum yields for Trp decomposition were determined at 5%, 20% and 100% O-2, in the presence of ferricyanide and D2O to elucidate the mechanism of action of AGEs. Type-I mechanism proved to be the most efficient pathway for AGE-sensitized Trp decomposition at low oxygen concentration. Photocrosslinking of lens proteins and crystallin fractions due to Type-I interaction was observed. The influence of the oxygen concentration and additives was also studied. The results show that both Type-I mechanism and oxygen-mediated reactions contribute to protein crosslinking. Carbonyl group formation due to protein photo-oxidation was detected with Oxyblot technique. The generation of high levels of hydrogen peroxide during the irradiations was detected and attributed mainly to Type-I reactions. The results support that AGEs act preferentially as Type-I sensitizers at the low oxygen concentration found in the lens and are capable of inducing protein crosslinking, oxidation and peroxide formation.