Bisby R H, Parker A W
Department of Biological Sciences, University of Salford, United Kingdom.
Biochem Biophys Res Commun. 1998 Mar 6;244(1):263-7. doi: 10.1006/bbrc.1998.8245.
The oxidation of the antioxidants dihydrolipoate and lipoamide by triplet duroquinone (3DQ) has been studied by laser flash photolysis and time-resolved resonance Raman (TR3) spectroscopy. Reaction of 3DQ with lipoamide by electron transfer [k(H2O)/k(D2O approximately 1] was more rapid than with dihydrolipoate, in which a proton is also involved [k(H2O)/k(D2O approximately 2]. For dihydrolipoate at neutral pH the undeprotonated form was the major reactive species with k approximately 10(9) dm3 mol-1 s-1. At higher pH values the reaction of ionised (thiolate) forms was observed with k > or = 4 x 10(9) dm3 mol-1 s-1. The electron transfer mechanism of reaction between 3DQ and lipoamide was confirmed by TR3 spectra in which formation of the durosemiquinone radical anion and lipoamide disulfide radical cation (RSS+.) was observed.
通过激光闪光光解和时间分辨共振拉曼光谱（TR3）研究了三重态杜醌（3DQ）对抗氧化剂二氢硫辛酸酯和硫辛酰胺的氧化作用。3DQ与硫辛酰胺通过电子转移反应（k(H₂O)/k(D₂O)约为1）比与二氢硫辛酸酯反应更快，后者还涉及一个质子（k(H₂O)/k(D₂O)约为2）。对于中性pH下的二氢硫辛酸酯，未去质子化形式是主要反应物种，k约为10⁹ dm³ mol⁻¹ s⁻¹。在较高pH值下，观察到离子化（硫醇盐）形式的反应，k≥4×10⁹ dm³ mol⁻¹ s⁻¹。TR3光谱证实了3DQ与硫辛酰胺之间反应的电子转移机制，其中观察到了杜半醌自由基阴离子和硫辛酰胺二硫化物自由基阳离子（RSS⁺·）的形成。
