Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim, Norway.
Photosynth Res. 2012 Apr;112(1):75-9. doi: 10.1007/s11120-012-9739-4. Epub 2012 Apr 6.
The temporal profile of the phosphorescence of singlet oxygen endogenously photosensitized by photosystem II (PSII) reaction centre (RC) in an aqueous buffer has been recorded using laser excitation and a near infrared photomultiplier tube. A weak emission signal was discernible, and could be fitted to the functional form a[exp(-t/τ(2) - exp(-t/τ(1)], with a > 0 and τ(2) > τ(1). The value of τ(2) decreased from 11.6 ± 0.5 μs under aerobic conditions to 4.1 ± 0.2 μs in oxygen-saturated samples, due to enhanced bimolecular quenching of the donor triplet by oxygen, whereas that of τ(1), identifiable with the lifetime of singlet oxygen, was close to 3 μs in both cases. Extrapolations based on the low amplitude of the emission signal of singlet oxygen formed by PSII RC in the aqueous buffer and the expected values of τ(1) and τ(2) in chloroplasts indicate that attempts to analyse the temporal profile of singlet oxygen in chloroplasts are unlikely to be rewarded with success without a significant advance in the sensitivity of the detection equipment.
使用激光激发和近红外光电倍增管记录了水相缓冲液中由光系统 II (PSII) 反应中心 (RC) 内源性光敏化的单线态氧的磷光的时间分布。可以分辨出一个微弱的发射信号，并可以拟合为 a[exp(-t/τ(2) - exp(-t/τ(1)]的函数形式，其中 a > 0 且 τ(2) > τ(1)。由于氧对供体三重态的双分子猝灭增强，τ(2)的值从有氧条件下的 11.6 ± 0.5 μs 降低到氧饱和样品中的 4.1 ± 0.2 μs，而 τ(1)可与单线态氧的寿命相对应，在两种情况下都接近 3 μs。基于 PSII RC 在水相缓冲液中形成的单线态氧的发射信号的低幅度和叶绿体中 τ(1)和 τ(2)的预期值的外推表明，如果没有检测设备灵敏度的显著提高，试图分析叶绿体中单线态氧的时间分布可能不会成功。
