Shimomura O, Johnson F H
Proc Natl Acad Sci U S A. 1978 Jun;75(6):2611-5. doi: 10.1073/pnas.75.6.2611.
The photoprotein aequorin emits light by an intramolecular reaction when Ca2+ is added under either aerobic or anaerobic conditions. Previously reported evidence has indicated two possibilities: (i) the functional group of aequorin is coelenterazine itself, a compond that plays key roles in the bioluminescence of various other types of organisms, or (ii) it is the enolized form of this compound. Present data rule out both of these possibilities, through elucidation of the structure of the yellow compound that is split off aequorin by treatment with NaHSO3. The yellow compound is now shown to be a tertiary alcohol of coelenterazine on the basis of chemical reactions, mass spectral data, and relationships to known derivatives of coelenterazine. From this structure and the method of forming the yellow compound from aequorin, aequorin evidently contains a peroxide of coelenterazine as the active group. The presence of such a peroxide is consistent with the fact that aequorin yields free coelenterazine upon treatment with Na2S2O4. Although there is no applicable technique at present to determine with assurance the specific state of the peroxide in the protein, a study with 18O tracer indicates that a linear peroxide structure is more likely than the alternative possibility of a dioxetane structure.
当在有氧或无氧条件下添加Ca2+时，光蛋白水母发光蛋白通过分子内反应发光。先前报道的证据表明有两种可能性：（i）水母发光蛋白的官能团是腔肠素本身，该化合物在其他各种生物的生物发光中起关键作用，或者（ii）它是该化合物的烯醇化形式。目前的数据通过阐明用NaHSO3处理从水母发光蛋白中分离出的黄色化合物的结构，排除了这两种可能性。基于化学反应、质谱数据以及与腔肠素已知衍生物的关系，现在表明该黄色化合物是腔肠素的叔醇。根据这个结构以及从水母发光蛋白形成黄色化合物的方法，水母发光蛋白显然含有腔肠素过氧化物作为活性基团。这种过氧化物的存在与水母发光蛋白在用Na2S2O4处理时产生游离腔肠素这一事实相一致。尽管目前没有适用的技术来确定蛋白质中过氧化物的具体状态，但一项用18O示踪剂的研究表明，线性过氧化物结构比二氧杂环丁烷结构的另一种可能性更有可能。
