Khabiri Faryar, Hagens Ralf, Smuda Christoph, Soltau Andreas, Schreiner Volker, Wenck Horst, Wittern Klaus-Peter, Duchstein Hans-Jürgen, Mei Weiping
F&E cosmed, Beiersdorf AG, Hamburg, Germany.
Skin Res Technol. 2008 Feb;14(1):103-11. doi: 10.1111/j.1600-0846.2007.00205.x.
BACKGROUND/PURPOSE: Oxidation of proteins and amino acids is associated with generation of ultraweak photon emission (UPE), which may be used to assess oxidative processes in the skin in a non-invasive way. This first part of a series of reports addresses the physicochemical basis of oxidation-induced UPE in the skin, with a special focus on the contribution of amino acid oxidation.
UPE of biological samples and protein/amino acid solutions following oxidation with H(2)O(2) in the presence of Fe(2+) was recorded using a sensitive photomultiplier system. Signals were analyzed with regard to overall signal intensity and spectral distribution.
Increasing concentrations of H(2)O(2) in aqueous bovine serum albumin solutions induced linearly correlated UPE and protein carbonyl compounds, with a substantially higher sensitivity for the measurement of UPE. In single amino acid solutions, strong UPE signals were generated by oxidation from Phe, Trp, His, and Cys, and weak signals from Lys and Thr. Analysis of reaction products by MS revealed high oxidative material turnover for Cys and His, whereas barely detectable oxidative material turnover seems to be sufficient to generate a UPE signal of similar strength from Trp and Phe. Combination of different amino acids did not result in a simple addition of individual oxidation-induced UPE signals, but in interactions ranging from antagonism to clear synergism. Synergism was evident between Trp- and UPE-generating amino acids such as Thr, Cys, and His, with the strongest synergism by far observed between Trp and His. The strikingly different individual UPE spectra of His and Trp, despite being of comparable overall strength, were congruent with a pure Trp UPE spectrum after combining His with Trp in solution, indicating energy transfer between both amino acids. Combination of Trp and DNA, which also gives UPE signals following oxidation, did not result in a synergistically enhanced or antagonized overall UPE signal, but in a simple addition of individual UPE signals.
Measurement of UPE could be proven to be a highly sensitive method to assess oxidative processes in biological molecules. The reported data indicate that UPE generated by oxidation stressed skin is mainly due to non-fluorescent photon emission via Trp, whereby Trp acts as an energy receptor from other excited species of oxidation-modified amino acids.
背景/目的：蛋白质和氨基酸的氧化与超微弱光子发射（UPE）的产生有关，这可用于以非侵入性方式评估皮肤中的氧化过程。本系列报告的第一部分探讨了皮肤中氧化诱导UPE的物理化学基础，特别关注氨基酸氧化的作用。
使用灵敏的光电倍增管系统记录在Fe(2+)存在下用H₂O₂氧化后生物样品以及蛋白质/氨基酸溶液的UPE。对信号的总体强度和光谱分布进行分析。
在牛血清白蛋白水溶液中增加H₂O₂的浓度会诱导线性相关的UPE和蛋白质羰基化合物，测量UPE的灵敏度明显更高。在单一氨基酸溶液中，苯丙氨酸（Phe）、色氨酸（Trp）、组氨酸（His）和半胱氨酸（Cys）氧化会产生强烈的UPE信号，赖氨酸（Lys）和苏氨酸（Thr）产生微弱信号。通过质谱分析反应产物发现，半胱氨酸和组氨酸的氧化物质周转率很高，而色氨酸和苯丙氨酸似乎仅需 barely detectable（难以检测到的）氧化物质周转率就能产生强度相似的UPE信号。不同氨基酸的组合不会导致单个氧化诱导的UPE信号简单相加，而是存在从拮抗到明显协同的相互作用。色氨酸与产生UPE的氨基酸如苏氨酸、半胱氨酸和组氨酸之间存在协同作用，其中色氨酸和组氨酸之间观察到迄今为止最强的协同作用。组氨酸和色氨酸各自显著不同的UPE光谱，尽管总体强度相当，但在溶液中将组氨酸与色氨酸混合后与纯色氨酸UPE光谱一致，表明两种氨基酸之间存在能量转移。色氨酸与DNA的组合在氧化后也会产生UPE信号，不会导致总体UPE信号协同增强或拮抗，而是单个UPE信号简单相加。
UPE测量可被证明是评估生物分子中氧化过程的一种高度灵敏的方法。报告的数据表明，氧化应激皮肤产生的UPE主要是由于色氨酸通过非荧光光子发射产生的，其中色氨酸作为来自其他氧化修饰氨基酸激发态的能量受体。
