title: Studies on the binding of fulvic acid with transferrin by spectroscopic analysis.
abstract: Transferrin has shown potential in the delivery of anticancer drugs into primarily proliferating cancer cells that over-express transferrin receptors. Fulvic acid has a wide range of biological and pharmacological activities which caused widespread concerns, the interaction of fulvic acid with human serum transferrin (Tf) has great significance for gaining a deeper insight about anticancer activities of fulvic acid. In this study, the mechanism of interaction between fulvic acid and Tf, has been investigated by using fluorescence quenching, thermodynamics, synchronous fluorescence and circular dichroism (CD) under physiological condition. Our results have shown that fulvic acid binds to Tf and form a new complex, and the calculated apparent association constants are 5.04×10(8) M(-1), 5.48×10(7) M(-1), 7.38×10(6) M(-1) from the fluorescence quenching at 288 K, 298 K, and 310 K. The thermodynamic parameters indicate that hydrogen bonding and weak van der Waals are involved in the interaction between fulvic acid and Tf. The binding of fulvic acid to Tf causes the α-helix structure content of the protein to reduce, and resulting that peptide chains of Tf become more stretched. Our results have indicated a mechanism of the interaction between fulvic acid and Tf, which may provide information for possible design of methods to deliver drug molecules via transferrin to target tissues and cells effectively.
authors.affiliation: College of Chemical Engineering, Hebei United University, Tangshan, Hebei 063009, China. Electronic address: xfzhang@iccas.ac.cn.
authors.forename: Xiu-feng
authors.initials: XF
authors.lastname: Zhang
authors.affiliation: College of Chemical Engineering, Hebei United University, Tangshan, Hebei 063009, China.
authors.forename: Guang
authors.initials: G
authors.lastname: Yang
authors.affiliation: Department of Literature and Law Tangshan College, Tangshan, Hebei 063000, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Dong
authors.affiliation: College of Chemical Engineering, Hebei United University, Tangshan, Hebei 063009, China.
authors.forename: Yan-qin
authors.initials: YQ
authors.lastname: Zhao
authors.affiliation: College of Chemical Engineering, Hebei United University, Tangshan, Hebei 063009, China.
authors.forename: Xiao-ran
authors.initials: XR
authors.lastname: Sun
authors.affiliation: College of Chemical Engineering, Hebei United University, Tangshan, Hebei 063009, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.affiliation: College of Chemical Engineering, Hebei United University, Tangshan, Hebei 063009, China.
authors.forename: Hong-bo
authors.initials: HB
authors.lastname: Chen
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000378:metabolism*; D001578:Benzopyrans / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D002942:Circular Dichroism; D006801:Humans; D006860:Hydrogen Bonding; D008958:Models, Molecular; D011485:Protein Binding; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D014168:Transferrin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D001578:Benzopyrans; D014168:Transferrin; C005023:fulvic acid
keywords: Circular dichroism; Fluorescence quenching; Fulvic acid; Thermodynamic parameters; Transferrin