Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405, Orsay, France.
INFIQC (CONICET-UNC). Departamento de Fisicoquímica, Fac. de Ciencias Químicas. Centro Láser de Ciencias Moleculares., Universidad Nacional de Córdoba, Ciudad Universitaria Pabellón Argentina, X5000HUA, Córdoba, Argentina.
Chemphyschem. 2023 Jan 17;24(2):e202200561. doi: 10.1002/cphc.202200561. Epub 2022 Oct 25.
The photodynamics of protonated tryptophan and its mono hydrated complex TrpH -H O has been revisited. A combination of steady-state IR and UV cryogenic ion spectroscopies with picosecond pump-probe photodissociation experiments sheds new lights on the deactivation processes of TrpH and conformer-selected TrpH -H O complex, supported by quantum chemistry calculations at the DFT and coupled-cluster levels for the ground and excited states, respectively. TrpH excited at the band origin exhibits a transient of less than 100 ps, assigned to the lifetime of the excited state proton transfer (ESPT) structure. The two experimentally observed conformers of TrpH -H O have been assigned. A striking result arises from the conformer-selective photodynamics of TrpH -H O, in which a single water molecule inserted in between the ammonium and the indole ring hinders the barrierless ESPT reaction responsible for the ultra-fast deactivation process observed in the other conformer and in bare TrpH .
质子化色氨酸及其单水合复合物 TrpH -H 2 O 的光动力学已经被重新研究。通过稳态 IR 和 UV 低温离子光谱学与皮秒泵浦探针光解实验的结合，结合 DFT 和耦合簇理论分别对基态和激发态的量子化学计算，为 TrpH 和构象选择的 TrpH -H 2 O 复合物的失活过程提供了新的线索。在带原点处激发的 TrpH 表现出小于 100 ps 的瞬变，这归因于激发态质子转移（ESPT）结构的寿命。已经对 TrpH -H 2 O 的两种实验观察到的构象进行了分配。一个惊人的结果来自于 TrpH -H 2 O 的构象选择性光动力学，其中单个水分子插入铵和吲哚环之间，阻碍了无势垒的 ESPT 反应，而这种反应负责观察到在其他构象和裸 TrpH 中超快失活过程。
