物理化学学报 >> 2009, Vol. 25 >> Issue (01): 25-29.doi: 10.3866/PKU.WHXB20090105

研究论文 上一篇    下一篇

牛血清白蛋白的光损伤和光氧化机理

程伶俐; 赵萍; 王玫; 朱慧; 朱融融; 孙晓宇; 汪世龙   

  1. 同济大学生命科学与技术学院, 上海 200092
  • 收稿日期:1900-01-01 修回日期:1900-01-01 发布日期:2008-12-31
  • 通讯作者: 汪世龙 E-mail:wsl@mail.tongji.edu.cn

Photodamage and Photooxidation Mechanisms of Bovine Serum Albumin

CHENG Ling-Li; ZHAO Ping; WANG Mei; ZHU Hui; ZHU Rong-Rong; SUN Xiao-Yu; WANG Shi-Long   

  1. School of Life Science and Technology, Tongji University, Shanghai 200092, P. R. China
  • Received:1900-01-01 Revised:1900-01-01 Published:2008-12-31
  • Contact: WANG Shi-Long E-mail:wsl@mail.tongji.edu.cn

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摘要： 运用激光闪光光解瞬态吸收技术, 在266 nm激光激励下, 研究了牛血清白蛋白(BSA)光损伤和被SO4-·单电子氧化的反应机理, 表征了反应过程中生成的自由基. 结果表明, 在266 nm激光照射下, BSA可同时发生光电离和光激发, 生成色氨酸阳离子自由基(Trp/NH+·), 由Trp/NH+·快速脱质子形成的色氨酸中性自由基(Trp/N·)及色氨酸三重激发态(3Trp*), 3Trp*再与酪氨酸(Tyr)发生分子内电子转移生成酪氨酸中性自由基(Tyr/O·). 在SO4-·单电子氧化的反应中, 借助减谱技术, 求得BSA中Tyr和色氨酸(Trp)自由基的表观生成速率常数, 但未发现分子内电子转移现象, 阐明了SO4-·自由基是通过与BSA中的Tyr和Trp发生电子转移反应来氧化BSA的, SO4-·氧化BSA的反应速率常数为1.51×1010 L·mol-1·s-1, 从而为进一步研究血清白蛋白的氧化还原代谢过程提供理论基础.

关键词: 牛血清白蛋白, 光电离, 光激发, 电子转移, 单电子氧化

Abstract: Photodamage and photooxidation mechanisms of bovine serumalbumin (BSA) as induced by UVradiation
and one-electron oxidation by SO4-· were investigated by 266 nm laser flash photolysis. BSA can be photoionized and photoexcited by 266 nm photons to give tryptophan (Trp)/NH+·, Trp/N· resulting from the rapid deprotonation of Trp/NH+·, and 3Trp*. Through intermolecular electron transfer between 3Trp* and tyrosine (Tyr), Tyr/O· was produced. In one-electron oxidation of BSA by SO4-· the apparent set up rate constants of Tyr and Trp radicals were calculated but intermolecular electron transfer was not observed. We propose that SO4-· oxidizes BSA by electron transfer to the Tyr and Trp of BSA with a rate constant of 1.51×1010 L·mol-1·s-1. This research provides an introductory theory to enable further study on the redox metabolic process of BSA.

Key words: Bovine serumalbumin, Photo-ionization, Photo-excitation, Electron transfer, One-electron oxidization