title: Affinity of a mononuclear monofunctional anticancer Pt(II)  complex to human serum albumin: a spectroscopic  approach.
abstract: The interaction of a mononuclear monofunctional anticancer Pt(II) complex, [PtLCl]Cl (L = 4′-bis(pyridine-2-ylmethyl)amino-2-phenylbenzothiazole) (1), and human serum albumin (HSA) was investigated under physiological conditions using UV–Vis absorption, circular dichroism, fluorescence, and synchronous fluorescence. The experimental results suggested that the Pt(II) complex could bind to HSA, induce conformation and microenvironmental changes of HSA with a moderate binding affinity, and quench the intrinsic fluorescence of HSA through a static quenching mechanism. The thermodynamic parameters, ΔG°, ΔH°, and ΔS°, calculated at different temperatures, indicated that the binding reaction was spontaneous and hydrophobic forces and π–π stacking played major roles in the association. Based on the number of binding sites, it was considered that one molecule of complex 1 could bind to a single site of HSA. In view of the results of site marker competition experiments, the reactive site of HSA to complex 1 mainly located in subdomain IIA (site I). Moreover, the binding distance, r, between donor (HSA) and acceptor (complex 1) was 4.69 nm according to Förster nonradiation energy transfer theory. The present study provides relevant and useful information that can be used for the design and application of mononuclear monofuctional Pt(II) complexes in biomedical sciences.
authors.affiliation: Hubei Collaborative Innovation Center for Rare Metal Chemistry, Hubei Key Laboratory of Pollutant Analysis & Reuse Technology, College of Chemistry and Chemical Engineering, Hubei Normal University, Huangshi 435002, People’s Republic of China. chenzf1979@163.com
authors.forename: Zhanfen
authors.initials: Z
authors.lastname: Chen
authors.forename: Shuping
authors.initials: S
authors.lastname: Zhang
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry*; D001665:Binding Sites; D056831:Coordination Complexes / Q000737:chemistry*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D009944:Organoplatinum Compounds / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D012709:Serum Albumin / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D013844:Thiazoles / Q000737:chemistry*
chemical_list: D000970:Antineoplastic Agents; D056831:Coordination Complexes; D009944:Organoplatinum Compounds; D012709:Serum Albumin; D013844:Thiazoles