title: Serum albumin prevents protein aggregation and amyloid formation and retains chaperone-like activity in the presence of physiological ligands.
abstract: Although serum albumin has an established function as a transport protein, evidence is emerging that serum albumin may also have a role as a molecular chaperone. Using established techniques to characterize chaperone interactions, this study demonstrates that bovine serum albumin: 1) preferentially binds stressed over unstressed client proteins; 2) forms stable, soluble, high molecular weight complexes with stressed client proteins; 3) reduces the aggregation of client proteins when it is present at physiological levels; and 4) inhibits amyloid formation by both WT and L55P transthyretin. Although the antiaggregatory effect of serum albumin is maintained in the presence of physiological levels of Ca(2+) and Cu(2+), the presence of free fatty acids significantly alters this activity: stabilizing serum albumin at normal levels but diminishing chaperone-like activity at high concentrations. Moreover, here it is shown that depletion of albumin from human plasma leads to a significant increase in aggregation under physiologically relevant heat and shear stresses. This study demonstrates that serum albumin possesses chaperone-like properties and that this activity is maintained under a number of physiologically relevant conditions.
authors.affiliation: School of Molecular Bioscience and Discipline of Pharmacology, The University of Sydney, Sydney, New South Wales 2006, Australia.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Finn
authors.forename: Andrea C
authors.initials: AC
authors.lastname: Nunez
authors.forename: Margaret
authors.initials: M
authors.lastname: Sunde
authors.forename: Simon B
authors.initials: SB
authors.lastname: Easterbrook-Smith
mesh_terms: D000682:Amyloid / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D002417:Cattle; D006801:Humans; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism; D011228:Prealbumin / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D055550:Protein Stability; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000682:Amyloid; D018832:Molecular Chaperones; D011228:Prealbumin; D012710:Serum Albumin, Bovine