Vos Marten H, Balduzzi Elsa, Sorigué Damien, Aleksandrov Alexey
Laboratoire d'Optique et Biosciences, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France.
Institute of Biosciences and Biotechnologies, BIAM Cadarache, Aix-Marseille University, CEA, CNRS, 13108 Saint-Paul-lez-Durance, France.
Sci Adv. 2025 Sep 19;11(38):eadz1904. doi: 10.1126/sciadv.adz1904.
The initial photoproduct of the natural photoenzyme fatty acid photodecarboxylase involves the flavin anion radical flavin adenine dinucleotide (FAD). Using spectrally resolved ultrafast transient absorption spectroscopy, we demonstrate that FAD photoexcitation in the absence of substrate leads to the formation of the oxidized flavin FAD (the resting state in the catalytic cycle) within 100 femtoseconds. While this feature is similar to that occurring in flavoprotein oxidases, the ensuing photocycle is more complex. Upon excitation at the lowest-energy transition, the ejected electron is initially captured as a hydrated electron () before transferring to a secondary acceptor in 2.5 picoseconds and returning to the flavin in 37 picoseconds. This implies that can be generated within a protein environment, an unprecedented finding. This assessment is supported by molecular dynamics simulations showing an expansion of the flavin-binding pocket without substrate, allowing water molecules to fill the void. Our results may pave the way to developing unconventional photocatalytic processes.
天然光酶脂肪酸光脱羧酶的初始光产物涉及黄素阴离子自由基黄素腺嘌呤二核苷酸（FAD）。利用光谱分辨超快瞬态吸收光谱，我们证明在没有底物的情况下，FAD光激发在100飞秒内导致氧化型黄素FAD（催化循环中的静止状态）的形成。虽然这一特征与黄素蛋白氧化酶中发生的情况相似，但随后的光循环更为复杂。在最低能量跃迁处激发时， ejected电子最初作为水合电子（）被捕获，然后在2.5皮秒内转移到二级受体，并在37皮秒内返回黄素。这意味着可以在蛋白质环境中产生，这是一个前所未有的发现。分子动力学模拟支持了这一评估，模拟显示没有底物时黄素结合口袋会扩张，使水分子能够填充空隙。我们的结果可能为开发非常规光催化过程铺平道路。
