Singlet Oxygen in a Cell: Spatially Dependent Lifetimes and Quenching Rate Constants
Singlet Oxygen in a Cell: Spatially Dependent Lifetimes and Quenching Rate Constants
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DOI：
10.1021/ja807484b
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发表时间：
2009-01-14
影响因子：
15
通讯作者：
Ogilby, Peter R.
中科院分区：
文献类型：
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作者：
Kuimova, Marina K.;Yahioglu, Gokhan;Ogilby, Peter R.
单线态分子氧 O-2(a(1)Delta(g)) 可以在细胞内敏化剂的聚焦激光照射下由基态氧 O-2(X-3 Sigma(-)(g)) 在单细胞中产生。随后可以通过其 1270 nm 磷光 (a(1)Delta(g) -> X-3 Sigma(-)(g)）以亚细胞空间分辨率检测这种细胞毒性物质。单线态氧的寿命决定了其扩散距离，从而决定了单线态氧引发的细胞扰动发生的细胞内体积元素。在本研究中，监测了敏化剂二氢卟酚 (Chl) 和 5,10,15,20-四(N-甲基-4-吡啶基)-21H,23H-卟啉 (TMPyP) 产生的单线态氧的时间分辨磷光。这些分子位于活细胞的不同区域。数据表明，(i) 单线态氧寿命和(it) 通过添加 NaN3 进行单线态氧猝灭的速率常数取决于 Chl 还是 TMPyP 是光敏剂。这些观察结果可能反映了给定亚细胞域的化学和物理成分的差异（例如，空间依赖性氧和NaN3扩散系数），从而提供了单线态氧对细胞固有异质性作出反应的证据。因此，尽管细胞内寿命相对较长，但单线态氧不会从其产生位点扩散很远的距离。这是表观细胞内粘度相对较大的结果。
Singlet molecular oxygen, O-2(a(1)Delta(g)), can be created in a single cell from ground-state oxygen, O-2(X-3 Sigma(-)(g)), upon focused laser irradiation of an intracellular sensitizer. This cytotoxic species can subsequently be detected by its 1270 nm phosphorescence (a(1)Delta(g) -> X-3 Sigma(-)(g)) with subcellular spatial resolution. The singlet oxygen lifetime determines its diffusion distance and hence the intracellular volume element in which singlet-oxygen-initiated perturbation of the cell occurs. In this study, the time-resolved phosphorescence of singlet oxygen produced by the sensitizers chlorin (Chl) and 5,10,15,20-tetrakis(N-methyl-4-pyridyl)-21H,23H-porphine (TMPyP) was monitored. These molecules localize in different domains of a living cell. The data indicate that (i) the singlet oxygen lifetime and (it) the rate constant for singlet oxygen quenching by added NaN3 depend on whether Chl or TMPyP was the photosensitizer. These observations likely reflect differences in the chemical and physical constituency of a given subcellular domain (e.g., spatially dependent oxygen and NaN3 diffusion coefficients), thereby providing evidence that singlet oxygen responds to the inherent heterogeneity of a cell. Thus, despite a relatively long intracellular lifetime, singlet oxygen does not diffuse a great distance from its site of production. This is a consequence of an apparent intracellular viscosity that is comparatively large.