Department of Physical Chemistry, University of Bucharest, Bd. Regina Elisabeta 4-12, 030018, Bucharest, Romania.
J Mol Model. 2012 Sep;18(9):4381-7. doi: 10.1007/s00894-012-1444-x. Epub 2012 May 15.
Theoretical absorption and electronic circular dichroism (ECD) spectra predicted via time-dependent density functional theory (TDDFT) calculations on the neutral and four anionic species of fisetin, an achiral flavonoid, were used to rationalize the experimental absorption and induced circular dichroism (ICD) spectra of the ligand upon binding to human serum albumin (HSA). On this basis, the mechanism responsible for the appearance of the ICD signal was ascribed to a distortion of the conformation of bound fisetin. Furthermore, comparison of the simulated and experimental spectra revealed that two fisetin species bind to HSA, namely, the neutral molecule and the anion deprotonated at the hydroxyl group in position 7, in a 1:1 ratio. The coupling of the theoretical results with the experimental absorption and ICD data allows identification of the flavonoid species that bind to the protein and evaluation of their conformation in the binding site.
利用时间依赖密度泛函理论（TDDFT）计算对非那西汀的中性和四种阴离子物种的理论吸收和电子圆二色性（ECD）光谱进行预测，以解释配体与人血清白蛋白（HSA）结合时的实验吸收和诱导圆二色性（ICD）光谱。在此基础上，将 ICD 信号出现的原因归因于结合的非那西汀构象的扭曲。此外，模拟和实验光谱的比较表明，两种非那西汀物种以 1:1 的比例与 HSA 结合，即中性分子和在 7 位羟基处去质子化的阴离子。将理论结果与实验吸收和 ICD 数据相结合，可以识别与蛋白质结合的类黄酮物种，并评估它们在结合部位的构象。
