Among numerous bioluminescent organisms, firefly is the most studied one. Recent experiment proposed that sulfoluciferin (SLH₂) may serve as a storage form of luciferin (LH₂). In the present article, we employed density functional theory calculation to uncover the mechanism and detailed process of the storage and release reactions. Due to lack of available crystallographic structure of the related enzyme, the calculation was performed on a model system. For the storage reaction, possible amino acid residues were used for imitating the protein environment. For the release reaction, the dielectric constant of 3.0 was employed to simulate the polarity of the protein cavity. The computational results indicated that the reactions from LH₂ to SLH₂ and from SLH₂ to LH₂ are both exergonic, which favor the storage and release processes and coincide with the experimental observation. Basing on experimental and current theoretical study, we supplemented the stages of LH₂ storage and release in the entire bioluminescent cycle of firefly. The current theoretical calculation could inspire the study on LH₂ storage and release of other bioluminescent organisms.

中文翻译：

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萤火虫萤光素储存与释放的理论研究

在众多的发光生物中，萤火虫是研究最多的一种。最近的实验提出，硫荧光素 ( SLH ₂ ) 可以作为荧光素 ( LH ₂ ) 的一种储存形式。在本文中，我们采用密度泛函理论计算来揭示储存和释放反应的机理和详细过程。由于缺乏相关酶的可用晶体结构，因此在模型系统上进行了计算。对于储存反应，可能的氨基酸残基用于模拟蛋白质环境。对于释放反应，采用介电常数 3.0 来模拟蛋白质腔的极性。计算结果表明，来自LH _2的反应到SLH ₂和从SLH ₂到LH ₂都是exergonic，有利于储存和释放过程，与实验观察一致。在实验和现有理论研究的基础上，我们补充了萤火虫整个发光周期中LH _{2的储存和释放阶段。}目前的理论计算可以启发对其他生物发光生物的LH ₂储存和释放的研究。