Abstract

It is believed that one of the causes of photodamage to the retina is the accumulation of all-trans-retinal (ATR) in the visual cells. However, the ATR is formed during photolysis inside the disk of the photoreceptor cell and transferred to the cytoplasm of the cell, where it is converted with a high yield to retinol, a nonphototoxic compound. Inside the disk, where ATR can accumulate, it can form Schiff bases, which are also not phototoxic compounds, with the amino groups of proteins and lipids. In addition, the resulting free retinal (R) isomers bind to specific retinal-binding proteins that can shield them from oxygen. Thus, the question on the concentrations in which free ATR can accumulate inside a cell is ambiguous. In this study, it is proposed to evaluate the concentration of free ATR in a cell by the yield of the excited triplet state, since neither the Schiff bases of ATR nor retinol are transformed into an excited triplet state. It is shown that 70% of ATR form Schiff bases in the equilibrium state in the native cell. This significantly reduces the likelihood that ATR is the main inducer of photodamage. Moreover, it is shown that the quantum yield of the formation reaction of an excited triplet state of R when it is bound to interfotoreceptor proteins is significantly reduced.

中文翻译：

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脉冲光解法研究视网膜及其衍生物在感光细胞中的光毒性

摘要

认为对视网膜造成光损伤的原因之一是全反式的积累。视细胞中的-视网膜（ATR）。但是，ATR是在光解过程中在感光细胞的圆盘内部形成的，并转移到细胞的细胞质中，然后以高收率转化为视黄醇（一种非光毒性化合物）。在ATR可以在其中积累的磁盘内部，它可以与蛋白质和脂质的氨基形成Schiff碱，这也不是光毒性化合物。此外，所得的游离视网膜（R）异构体会与特定的视网膜结合蛋白结合，从而使它们免受氧气的影响。因此，关于游离ATR可以在细胞内积累的浓度的问题是模棱两可的。在这项研究中，由于ATR的席夫碱和视黄醇均未转化为激发的三重态，因此建议通过激发三重态的产率来评估细胞中游离ATR的浓度。结果表明，天然细胞中处于平衡状态的ATR中有70％形成席夫碱。这显着降低了ATR是光损伤的主要诱因的可能性。此外，显示出当R与受体间蛋白结合时，R的激发三重态的形成反应的量子产率显着降低。