Limones-Herrero Daniel, Palumbo Fabrizio, Vendrell-Criado Victoria, Andreu Inmaculada, Lence Emilio, González-Bello Concepción, Miranda Miguel A, Jiménez M Consuelo
Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, 46022, Valencia, Spain.
Unidad Mixta de Investigación UPV-Instituto de Investigación Sanitaria (IIS) La Fe, Hospital Universitari i Politècnic La Fe, Avenida de Fernando Abril Martorell 106, 46026, Valencia, Spain.
Spectrochim Acta A Mol Biomol Spectrosc. 2020 Feb 5;226:117652. doi: 10.1016/j.saa.2019.117652. Epub 2019 Oct 12.
Transient absorption spectroscopy in combination with in silico methods has been employed to study the interactions between human serum albumin (HSA) and the anti-psychotic agent chlorpromazine (CPZ) as well as its two demethylated metabolites (MCPZ and DCPZ). Thus, solutions containing CPZ, MCPZ or DCPZ and HSA (molar ligand:protein ratios between 1:0 and 1:3) were submitted to laser flash photolysis and the ΔA value at λ = 470 nm, corresponding to the triplet excited state, was monitored. In all cases, the protein-bound ligand exhibited higher ΔAmax values measured after the laser pulse and were also considerably longer-lived than the non-complexed forms. This is in agreement with an enhanced hydrophilicity of the metabolites, due to the replacement of methyl groups with H that led to a lower extent of protein binding. For the three compounds, laser flash photolysis displacement experiments using warfarin or ibuprofen indicated Sudlow site I as the main binding site. Docking and molecular dynamics simulation studies revealed that the binding mode of the two demethylated ligands with HSA would be remarkable different from CPZ, specially for DCPZ, which appears to come from the different ability of their terminal ammonium groups to stablish hydrogen bonding interactions with the negatively charged residues within the protein pocket (Glu153, Glu292) as well as to allocate the methyl groups in an apolar environment. DCPZ would be rotated 180° in relation to CPZ locating the aromatic ring away from the Sudlow site I of HSA.
瞬态吸收光谱法结合计算机模拟方法已被用于研究人血清白蛋白（HSA）与抗精神病药物氯丙嗪（CPZ）及其两种去甲基化代谢物（MCPZ和DCPZ）之间的相互作用。因此，将含有CPZ、MCPZ或DCPZ以及HSA（配体与蛋白质的摩尔比在1:0至1:3之间）的溶液进行激光闪光光解，并监测在λ = 470 nm处对应于三重态激发态的ΔA值。在所有情况下，与蛋白质结合的配体在激光脉冲后测得的ΔAmax值更高，并且其寿命也比未络合形式长得多。这与代谢物亲水性增强相一致，因为甲基被氢取代导致蛋白质结合程度降低。对于这三种化合物，使用华法林或布洛芬的激光闪光光解置换实验表明Sudlow位点I是主要结合位点。对接和分子动力学模拟研究表明，两种去甲基化配体与HSA的结合模式与CPZ有显著不同，特别是对于DCPZ，这似乎源于它们末端铵基团与蛋白质口袋内带负电荷残基（Glu153、Glu292）形成氢键相互作用以及在非极性环境中分配甲基的能力不同。DCPZ相对于CPZ会旋转180°，使芳香环远离HSA的Sudlow位点I。
