title: Enhancement of the binding affinity of methylene blue to site I in human serum albumin by cupric and ferric ions.
abstract: In this work, the binding characteristics of methylene blue (MB) to human serum albumin (HSA) and the influence of Cu(2+) and Fe(3+) on the binding affinity of MB to HSA were investigated using fluorescence, absorption, circular dichroism (CD) spectroscopy and molecular modelling. The results of competitive binding experiments using the site probes ketoprofen and ibuprofen as specific markers suggested that MB was located in site I within sub-domain IIA of HSA. The molecular modelling results agreed with the results of competitive site marker experiments and the results of CD spectra indicated that the interaction between MB and HSA caused the conformational changes in HSA. The binding affinity of MB to HSA was enhanced but to a different extent in the presence of Cu(2+) and Fe(3+), respectively, which indicated that the influence of different metal ions varied. Enhancement of the binding affinity of MB to HSA in the presence of Cu(2+) is due to the formation of Cu(2+)-HSA complex leading to the conformational changes in HSA, whereas in the presence of Fe(3+), enhancement of the binding affinity is due to the greater stability of the Fe(3+)-HSA-MB complex compared with the MB-HSA complex.
authors.affiliation: College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang, 110142, China.
authors.forename: Ling-Ling
authors.initials: LL
authors.lastname: He
authors.affiliation: College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang, 110142, China.
authors.forename: Yong-Xia
authors.initials: YX
authors.lastname: Wang
authors.affiliation: College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang, 110142, China.
authors.forename: Xiao-Xia
authors.initials: XX
authors.lastname: Wu
authors.affiliation: College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang, 110142, China.
authors.forename: Xian-Ping
authors.initials: XP
authors.lastname: Liu
authors.affiliation: School of Pharmaceutical Sciences, Liaoning University, Shenyang, 110036, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: School of Pharmaceutical Sciences, Liaoning University, Shenyang, 110036, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.affiliation: School of Pharmaceutical Sciences, Liaoning University, Shenyang, 110036, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
mesh_terms: D001665:Binding Sites; D002942:Circular Dichroism; D003300:Copper / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D006801:Humans; D007700:Kinetics; D008751:Methylene Blue / Q000737:chemistry*; D011485:Protein Binding; D012709:Serum Albumin / Q000737:chemistry*
chemical_list: D005290:Ferric Compounds; D012709:Serum Albumin; D003300:Copper; D008751:Methylene Blue
keywords: binding affinity; binding site; human serum albumin; metal ion; methylene blue