V.V. Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences, 3 Institutskaya Str., 630090 Novosibirsk, Russia.
Department of Natural Sciences, Department of Physics, Novosibirsk State University, 2 Pirogova Str., 630090 Novosibirsk, Russia.
Int J Mol Sci. 2023 Feb 7;24(4):3331. doi: 10.3390/ijms24043331.
Optical isomers of short peptide Lysine-Tryptophan-Lysine (Lys-{L/D-Trp}-Lys) and Lys-Trp-Lys with an acetate counter-ion were used to study photoinduced intramolecular and intermolecular processes of interest in photobiology. A comparison of L- and D-amino acid reactivity is also the focus of scientists' attention in various specialties because today, the presence of amyloid proteins with D-amino acids in the human brain is considered one of the leading causes of Alzheimer's disease. Since aggregated amyloids, mainly Aβ42, are highly disordered peptides that cannot be studied with traditional NMR and X-ray techniques, it is trending to explore the reasons for differences between L- and D-amino acids using short peptides, as in our article. Using NMR, chemically induced dynamic nuclear polarization (CIDNP) and fluorescence techniques allowed us to detect the influence of tryptophan (Trp) optical configuration on the peptides fluorescence quantum yields, bimolecular quenching rates of Trp excited state, and the photocleavage products formation. Thus, compared with the D-analog, the L-isomer shows a greater Trp excited state quenching efficiency with the electron transfer (ET) mechanism. There are experimental confirmations of the hypothesis about photoinduced ET between Trp and the CONH peptide bond, as well as between Trp and another amide group.
短肽赖氨酸-色氨酸-赖氨酸（Lys-{L/D-Trp}-Lys）和带有醋酸根 counter-ion 的赖氨酸-色氨酸-赖氨酸光学异构体被用于研究光生物学生物学中感兴趣的光诱导分子内和分子间过程。L-和 D-氨基酸反应性的比较也是科学家在各个专业领域关注的焦点，因为如今，人类大脑中存在含有 D-氨基酸的淀粉样蛋白被认为是导致阿尔茨海默病的主要原因之一。由于聚集的淀粉样蛋白主要是 Aβ42，是高度无序的肽，无法使用传统的 NMR 和 X 射线技术进行研究，因此人们倾向于使用短肽探索 L-和 D-氨基酸之间差异的原因，就像我们在文章中所做的那样。使用 NMR、化学诱导动态核极化 (CIDNP) 和荧光技术，我们能够检测色氨酸（Trp）光学构型对肽荧光量子产率、Trp 激发态双分子猝灭速率以及光裂解产物形成的影响。因此，与 D-类似物相比，L-异构体表现出更高的色氨酸激发态猝灭效率，其电子转移（ET）机制。实验证实了色氨酸与 CONH 肽键之间以及色氨酸与另一个酰胺基团之间光诱导 ET 的假设。
