Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China.
J Org Chem. 2021 Jan 15;86(2):1874-1881. doi: 10.1021/acs.joc.0c02788. Epub 2021 Jan 4.
As the only genetically encodable bioluminescent system among eukaryotes to date, bioluminescent fungi can unceasingly emit green light for days. Cross-reactions among four lineages of luminescent fungi suggest that all of them share a common bioluminescent mechanism. A series of excellent experiments by Yampolsky's group have revealed the key components in fungal bioluminescence (BL) from luciferin to light emission. However, the detailed underlying mechanism and processes remain unknown. By performing multireference and (time dependent) density functional theory calculations, we clearly described the bioluminescent process at the molecular and electronic state level. The fungal BL is initiated by the cycloaddition of O to luciferin to form an α-pyrone endoperoxide high-energy intermediate (). This oxygenation is not initiated by a single-electron transfer as it is in firefly BL, but it is explained by a charge transfer followed by a spin inversion mechanism. The thermolysis of generates oxyluciferin at the first singlet excited state (S) through a zwitterion intermediate (). A chemical form of the S-state oxyluciferin, -*, has the potential to be a light emitter. The current theoretical calculation provides great detail for deeply understanding the chemical processes in fungal BL and in chemiluminescence involving α-pyrone endoperoxide.
作为目前为止真核生物中唯一一种可遗传的生物发光系统，生物发光真菌可以持续数天发出绿光。四种发光真菌之间的交叉反应表明，它们都具有共同的生物发光机制。Yampolsky 小组进行了一系列出色的实验，揭示了真菌生物发光（BL）从荧光素到发光的关键组成部分。然而，其详细的潜在机制和过程仍然未知。通过进行多参考和（时变）密度泛函理论计算，我们在分子和电子态水平上清楚地描述了生物发光过程。真菌 BL 是由 O 与荧光素的环加成反应形成高能α-吡喃酮内过氧化物中间体（）引发的。这种氧合作用不是像萤火虫 BL 那样由单电子转移引发的，而是通过电荷转移和自旋反转机制来解释的。通过 zwitterion 中间体（），生成的 oxyluciferin 在第一单重激发态（S）中通过热解生成。S 态 oxyluciferin 的一种化学形式，-*，具有成为发光体的潜力。当前的理论计算为深入了解真菌 BL 和涉及α-吡喃酮内过氧化物的化学发光中的化学过程提供了详细信息。
