title: The interaction of human serum albumin with selected lanthanide and actinide ions: Binding affinities, protein unfolding and conformational changes.
abstract: Human serum albumin (HSA), the most abundant soluble protein in blood plays critical roles in transportation of biomolecules and maintenance of osmotic pressure. In view of increasing applications of lanthanides- and actinides-based materials in nuclear energy, space, industries and medical applications, the risk of exposure with these metal ions is a growing concern for human health. In present study, binding interaction of actinides/lanthanides [thorium: Th(IV), uranium: U(VI), lanthanum: La(III), cerium: Ce(III) and (IV)] with HSA and its structural consequences have been investigated. Ultraviolet-visible, Fourier transform-infrared, Raman, Fluorescence and Circular dichroism spectroscopic techniques were applied to study the site of metal ions interaction, binding affinity determination and the effect of metal ions on protein unfolding and HSA conformation. Results showed that these metal ions interacted with carbonyl (CO..:)/amide(N..-H) groups and induced exposure of aromatic residues of HSA. The fluorescence analysis indicated that the actinide binding altered the microenvironment around Trp214 in the subdomain IIA. Binding affinity of U(VI) to HSA was slightly higher than that of Th(IV). Actinides and Ce(IV) altered the secondary conformation of HSA with a significant decrease of α-helix and an increase of β-sheet, turn and random coil structures, indicating a partial unfolding of HSA. A correlation was observed between metal ion's ability to alter HSA conformation and protein unfolding. Both cationic effects and coordination ability of metal ions seemed to determine the consequences of their interaction with HSA. Present study improves our understanding about the protein interaction of these heavy ions and their impact on its secondary structure. In addition, binding characteristics may have important implications for the development of rational antidote for the medical management of health effects of actinides and lanthanides.
authors.affiliation: Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai 85, India.
authors.forename: Manjoor
authors.initials: M
authors.lastname: Ali
authors.affiliation: Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai 85, India. Electronic address: amitk@barc.gov.in.
authors.forename: Amit
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 85, India.
authors.forename: Mukesh
authors.initials: M
authors.lastname: Kumar
authors.affiliation: Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai 85, India.
authors.forename: Badri N
authors.initials: BN
authors.lastname: Pandey
mesh_terms: D008671:Actinoid Series Elements / Q000737:chemistry*; D002942:Circular Dichroism; D006801:Humans; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D011487:Protein Conformation; D012709:Serum Albumin / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D008671:Actinoid Series Elements; D028581:Lanthanoid Series Elements; D012709:Serum Albumin
keywords: Human serum albumin; Metal–protein interactions; Structural alterations