Bou-Abdallah Fadi, Chasteen N Dennis, Lesser Michael P
Department of Chemistry, University of New Hampshire, Durham, NH 03824, USA.
Biochim Biophys Acta. 2006 Nov;1760(11):1690-5. doi: 10.1016/j.bbagen.2006.08.014. Epub 2006 Aug 25.
Green fluorescent proteins (GFP) are widely used in vivo molecular markers. These proteins are particularly resistant, and maintain function, under a variety of cellular conditions such as pH extremes and elevated temperatures. Green fluorescent proteins are also abundant in several groups of marine invertebrates including reef-forming corals. While molecular oxygen is required for the post-translational maturation of the protein, mature GFPs are found in corals where hyperoxia and reactive oxygen species (ROS) occur due to the photosynthetic activity of algal symbionts. In vitro spin trapping electron paramagnetic resonance and spectrophotometric assays of superoxide dismutase (SOD)-like enzyme activity show that wild type GFP from the hydromedusa, Aequorea victoria, quenches superoxide radicals (O2*-)) and exhibits SOD-like activity by competing with cytochrome c for reaction with O2*-. When exposed to high amounts of O2*- the SOD-like activity and protein structure of GFP are altered without significant changes to the fluorescent properties of the protein. Because of the distribution of fluorescent proteins in both the epithelial and gastrodermal cells of reef-forming corals we propose that GFP, and possibly other fluorescent proteins, can provide supplementary antioxidant protection.
绿色荧光蛋白（GFP）是广泛应用的体内分子标记物。这些蛋白质具有特别的抗性，在多种细胞条件下，如极端pH值和高温环境中仍能保持功能。绿色荧光蛋白在包括造礁珊瑚在内的几类海洋无脊椎动物中也很丰富。虽然蛋白质的翻译后成熟需要分子氧，但在由于藻类共生体的光合活性而出现高氧和活性氧（ROS）的珊瑚中也发现了成熟的绿色荧光蛋白。对来自水螅水母维多利亚多管水母的野生型绿色荧光蛋白进行体外自旋捕获电子顺磁共振和超氧化物歧化酶（SOD）样酶活性的分光光度测定表明，它能淬灭超氧自由基（O2*-），并通过与细胞色素c竞争与O2*-反应而表现出SOD样活性。当暴露于大量O2*-时，绿色荧光蛋白的SOD样活性和蛋白质结构会发生改变，但其荧光特性没有明显变化。由于荧光蛋白在造礁珊瑚的上皮细胞和胃皮细胞中均有分布，我们认为绿色荧光蛋白以及其他可能的荧光蛋白可以提供补充性抗氧化保护。
