title: Mobilization of Cd from human serum albumin by small molecular weight thiols.
abstract: Although the toxic metal Cd is an established human nephrotoxin, little is known about the role that interactions with plasma constitutents play in determining its mammalian target organs. To gain insight, a Cd-human serum albumin (HSA) complex was analyzed on a system consisting of size exclusion chromatography (SEC) coupled on-line to a flame atomic absorption spectrometer (FAAS). Using phosphate buffered saline (pH 7.4) as the mobile phase, we investigated the effect of 1-10mM oxidized glutathione (GSSG), l-cysteine (Cys), l-glutathione (GSH), or N-acetyl-l-cysteine (NAC) on the elution of Cd. As expected, GSSG did not mobilize Cd from the Cd-HSA complex up to a concentration of 4mM. With 1.0mM NAC, ∼30% of the injected Cd-HSA complex eluted as such, while the mobilized Cd was lost on the column. With 1.0mM of Cys or GSH, no parent Cd-HSA complex was detected and 88% and 82% of the protein bound Cd eluted close to the elution volume, likely in form of Cd(Cys)2 and a Cd-GSH 1:1 complex. Interestingly, with GSH and NAC concentrations >4.0mM, a Cd double peak was detected, which was rationalized in terms of the elution of a polynuclear Cd complex baseline-separated from a mononuclear Cd complex. In contrast, mobile phases which contained Cys concentrations ≥2mM resulted in the detection of only a single Cd peak, probably Cd(Cys)4. Our results establish SEC-FAAS as a viable tool to probe the mobilization of Cd from binding sites on plasma proteins at near physiological conditions. The detected complexes between Cd and Cys or GSH may be involved in the translocation of Cd to mammalian target organs.
authors.affiliation: Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4 Canada.
authors.forename: Thomas T
authors.initials: TT
authors.lastname: Morris
authors.affiliation: Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4 Canada.
authors.forename: Jennifer L A
authors.initials: JL
authors.lastname: Keir
authors.affiliation: Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4 Canada.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Boshart
authors.affiliation: Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4 Canada.
authors.forename: Victor P
authors.initials: VP
authors.lastname: Lobanov
authors.affiliation: Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4 Canada.
authors.forename: Anthony M A
authors.initials: AM
authors.lastname: Ruhland
authors.affiliation: Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4 Canada.
authors.forename: Nishita
authors.initials: N
authors.lastname: Bahl
authors.affiliation: Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4 Canada. Electronic address: jgailer@ucalgary.ca.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Gailer
mesh_terms: D000111:Acetylcysteine / Q000378:metabolism; D002104:Cadmium / Q000378:metabolism*; D002850:Chromatography, Gel / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003545:Cysteine / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D011485:Protein Binding; D012709:Serum Albumin / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000378:metabolism
chemical_list: D012709:Serum Albumin; D013438:Sulfhydryl Compounds; D002104:Cadmium; D005978:Glutathione; D003545:Cysteine; D000111:Acetylcysteine
keywords: Albumin; Cd-specific detection; Hyphenation; SEC; Small molecular weight thiol; Target organ