title: Spectroscopic studies of the interaction between hypocrellin B and human serum albumin.
abstract: Previous work has proved that hypocrellin B (HB) binds to human serum albumin (HSA) at a specific site instead of distributed randomly on the surface of a protein. In the current work, further investigation by using bilirubin as a site I marker indicates that HB can compete for the same site with bilirubin, suggesting that the HB binding site is located at sub-domain IIA (site I) of HSA. Moreover, bound to HSA, the HB fluorescence was found to be pH sensitive in physiological range (pH 6.0-8.0). The increasing of binding constant of HB to HSA in the pH range 6-8 also indicates that the N<-->B transition modulates the microenvironment changes of the binding site and influences considerably the binding between HB and HSA. Furthermore, picosecond time-resolved fluorescence spectra of HB-HSA complex in PBS indicate an additional short-lived component compared to that for HB in benzene, which may be assigned to the process of electron transfer from Trp-214 to HB.
authors.affiliation: Key Laboratory of Photochemistry, Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, People's Republic of China.
authors.forename: Baozhong
authors.initials: B
authors.lastname: Zhao
authors.forename: Liming
authors.initials: L
authors.lastname: Song
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.forename: Jie
authors.initials: J
authors.lastname: Xie
authors.forename: Jingquan
authors.initials: J
authors.lastname: Zhao
mesh_terms: D001663:Bilirubin / Q000737:chemistry; D001665:Binding Sites; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D010569:Perylene / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D011485:Protein Binding; D011809:Quinones / Q000737:chemistry* / Q000494:pharmacology; D012709:Serum Albumin / Q000737:chemistry* / Q000187:drug effects; D013050:Spectrometry, Fluorescence / Q000379:methods; D013329:Structure-Activity Relationship; D013997:Time Factors
chemical_list: D011809:Quinones; D012709:Serum Albumin; D010569:Perylene; D001663:Bilirubin; C064522:hypocrellin B