| Human serum albumin(HSA)as the most abundant protein in plasma functions as one of the major binders/carriers of fatty acid and drugs,since it transports a wide variety of drugs to target organs and tissues,HSA plays an essential role in pharmacokinetics and delivery of drugs.In the past forty years,the interaction between albumin and compounds is research hotspots both at home and abroad.Furthermore,human serum albumin has been extensively studied as drug carrier.In this paper,under the simulated physiological conditions,the interaction of small molecule drugs and HSA was studied by X-ray diffraction,antitumor activity in vitro and spectroscopy.This thesis can be divided into three parts:1.structural basis and anticancer properties of ruthenium-based drug complexed with human serum albumin;2.structural basis of non-steroidal anti-inflammatory drug diclofenac binding to human serum albumin;3.binding and anticancer properties of plumbagin with human serum albumin.we studied the structure and anticancer properties of the ruthenium-based compound[RuCl5(ind)]2-in complex with HSA.The structure revealed that[RuCl5(ind)]2-has two binding sites in HSA.In the IB subdomain,[RuCl5(ind)]2-binds to a new sub-site by coordinating with His-146.In the IIA subdomain,ruthenium(?)of[RuCl5(ind)]2-binds to the hydrophobic cavity and forms coordination bonds by replacing chlorine atoms with the His-242 and Lys-199 residues of HSA.Interestingly,[RuCl5(ind)]2-,together with HSA,can enhance cytotoxicity by two to five times in cancer cells but has no effect on normal cells in vitro.Compared with unbound drug,the HSA-[RuCl5(ind)]2-complex promotes MGC-803 cell apoptosis and also has a stronger ability for cell cycle arrest at the G2 phase in MGC-803.In conclusion,this study will guide the rational design and development of ruthenium-containing or ruthenium-centered drugs and an HSA delivery system for ruthenium-based drugs.To understand binding characterization of nonsteroidal anti-inflammatory drugs to HSA,we studied the interactions of diclofenac and HSA by X-ray crystallography.HSA-palmitic acid-diclofenac structure reveals two distinct binding sites for three diclofenac in HSA.One diclofenac is located at the IB subdomain,and its carboxylate group project toward polar environment,forming hydrogen bond with one water molecule.The other two diclofenac molecules co-bind in big hydrophobic cavity of the IIA subdomain without interactive association.Among them,one binds in main chamber of big hydrophobic cavity,its carboxylate group forms hydrogen bonds with Lys199 and Arg218,as well as one water molecule,whereas another diclofenac binds in side chamber,its carboxylate group project out cavity,forming hydrogen bond with Ser480.These results significantly advance our understanding of the structure and binding behavior of non-steroidal anti-inflammatory drugs,providing the molecular basis for future design and improvement of DIC-derived drugs.Plumbagin has received extensive attention as a promising anticancer drug.this part,we investigated the binding and anticancer properties of plumbagin with human serum albumin.Fluorescence results demonstrated that plumbagin interacts with human serum albumin,although its binding affinity may be affected to various extents by different compounds.The human serum albumin-plumbagin complex structure revealed that plumbagin binds to the hydrophobic cavity in the IIA subdomain of human serum albumin through hydrogen bonding and hydrophobic interactions.The plumbagin-human serum albumin complex enhances cytotoxicity by 2-to 3-fold particularly in cancer cells but has no effect on normal cells in vitro.Compared with the unbound drug,the human serum albumin-plumbagin complex promotes HeLa cell apoptosis and has a stronger ability for cell cycle arrest at the G2/M phase in HeLa cells.In conclusion,this study con-tributes to the rational design and development of plumbagin-based drugs and a drug-human serum albumin delivery system. |
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