Ward W W, Cormier M J
Proc Natl Acad Sci U S A. 1975 Jul;72(7):2530-4. doi: 10.1073/pnas.72.7.2530.
Photoproteins, which emit light in an oxygen-independent intramolecular reaction initiated by calcium ions, have been isolated from several bioluminescent organisms, including the hydrozoan jellyfish Aequorea and the ctenophore Mnemiopsis. The system of a related anthozoan coelenterate, the sea pansy Renilla reniformis, however, is oxygen dependent, requiring two organic components, luciferin and luciferase. Previously published indirect evidence indicates that photoproteins may contain a Renilla-type luciferin. We have now extracted in high yield a Renilla-type luciferin from three photoproteins, aequorin (45% yield), mnemiopsin (98% yield), and berovin (85% yield). Photoprotein luciferin, released from the holoprotein by mercaptoethanol treatment and separated from apo-photoprotein by gel filtration, no longer responds to calcium but now requires luciferase and O2 for light production. Photoprotein luciferin is identical to Renilla luciferin with respect to reaction kinetics and bioluminescence spectral distribution. In view of these results, the generally accepted hypothesis that the photoprotein chromophore is a protein-stabilized hydroperoxide of luciferin must be modified. We believe, instead, that the chromophore is free luciferin and that oxygen is bound as an oxygenated derivative of an amino-acid side chain of the protein. We propose the general term "coelenterate luciferin" to describe the light-producing chromophore from all bioluminescent coelenterates and ctenophores.
光蛋白可在由钙离子引发的与氧无关的分子内反应中发光，已从包括水螅水母海肾和栉水母在内的几种生物发光生物中分离出来。然而，相关的珊瑚虫腔肠动物海肾（Renilla reniformis）的发光系统是依赖氧的，需要两种有机成分，即荧光素和荧光素酶。先前发表过的间接证据表明，光蛋白可能含有海肾型荧光素。我们现在已从三种光蛋白——水母发光蛋白（产量为45%）、多管水母荧光蛋白（产量为98%）和贝鲁维亚光蛋白（产量为85%）中高产量地提取出海肾型荧光素。通过巯基乙醇处理从全蛋白中释放出来并通过凝胶过滤与脱辅基光蛋白分离的光蛋白荧光素，不再对钙有反应，但现在需要荧光素酶和氧气来产生光。光蛋白荧光素在反应动力学和生物发光光谱分布方面与海肾荧光素相同。鉴于这些结果，必须修改普遍接受的假设，即光蛋白发色团是一种由蛋白质稳定的荧光素氢过氧化物。相反，我们认为发色团是游离的荧光素，并且氧是以蛋白质氨基酸侧链的氧化衍生物形式结合的。我们提出用通用术语“腔肠动物荧光素”来描述所有生物发光腔肠动物和栉水母的发光发色团。
