Faculty of Chemistry, Institute of Theoretical Chemistry, University of Vienna, Vienna, Austria.
Department of Chemistry, University of Warwick, Coventry, UK.
Nat Chem. 2022 Aug;14(8):914-919. doi: 10.1038/s41557-022-00950-z. Epub 2022 Jun 2.
Amino acids are among the building blocks of life, forming peptides and proteins, and have been carefully 'selected' to prevent harmful reactions caused by light. To prevent photodamage, molecules relax from electronic excited states to the ground state faster than the harmful reactions can occur; however, such photochemistry is not fully understood, in part because theoretical simulations of such systems are extremely expensive-with only smaller chromophores accessible. Here, we study the excited-state dynamics of tyrosine using a method based on deep neural networks that leverages the physics underlying quantum chemical data and combines different levels of theory. We reveal unconventional and dynamically controlled 'roaming' dynamics in excited tyrosine that are beyond chemical intuition and compete with other ultrafast deactivation mechanisms. Our findings suggest that the roaming atoms are radicals that can lead to photodamage, offering a new perspective on the photostability and photodamage of biological systems.
氨基酸是生命的基石之一，形成肽和蛋白质，并经过精心“选择”以防止光引起的有害反应。为了防止光损伤，分子从电子激发态更快地弛豫到基态，以至于有害反应无法发生；然而，这种光化学过程尚未完全被理解，部分原因是此类系统的理论模拟极其昂贵——只有较小的发色团是可及的。在这里，我们使用一种基于深度神经网络的方法研究了酪氨酸的激发态动力学，该方法利用了量子化学数据背后的物理原理，并结合了不同层次的理论。我们揭示了激发态酪氨酸中非常规且动态控制的“漫游”动力学，这超出了化学直觉，并与其他超快失活机制竞争。我们的发现表明，漫游原子是自由基，可能导致光损伤，为生物系统的光稳定性和光损伤提供了新的视角。
