title: Study of wild-type α-synuclein binding and orientation on gold nanoparticles.
abstract: The disruption of α-synuclein (α-syn) homeostasis in neurons is a potential cause of Parkinson's disease, which is manifested pathologically by the appearance of α-syn aggregates, or Lewy bodies. Treatments for neurological diseases are extremely limited. To study the potential use of gold nanoparticles (Au NPs) to limit α-syn misfolding, the binding and orientation of α-syn on Au NPs were investigated. α-Syn was determined to interact with 20 and 90 nm Au NPs via multilayered adsorption: a strong electrostatic interaction between α-syn and Au NPs in the hard corona and a weaker noncovalent protein-protein interaction in the soft corona. Spectroscopic and light-scattering titrations led to the determinations of binding constants for the Au NP α-syn coronas: for the hard corona on 20 nm Au NPs, the equilibrium association constant was 2.9 ± 1.1 × 10(9) M(-1) (for 360 ± 70 α-syn/NP), and on 90 nm Au NPs, the hard corona association constant was 9.5 ± 0.8 × 10(10) M(-1) (for 5300 ± 700 α-syn/NP). The binding of the soft corona was thermodynamically unfavorable and kinetically driven and was in constant exchange with "free" α-syn in solution. A protease digestion method was used to deduce the α-syn orientation and structure on Au NPs, revealing that α-syn absorbs onto negatively charged Au NPs via its N-terminus while apparently retaining its natively unstructured conformation. These results suggest that Au NPs could be used to sequester and regulate α-syn homeostasis.
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Jie An
authors.initials: JA
authors.lastname: Yang
authors.forename: Brittany J
authors.initials: BJ
authors.lastname: Johnson
authors.forename: Sway
authors.initials: S
authors.lastname: Wu
authors.forename: Wendy S
authors.initials: WS
authors.lastname: Woods
authors.forename: Julia M
authors.initials: JM
authors.lastname: George
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Murphy
mesh_terms: D000327:Adsorption; D000595:Amino Acid Sequence; D006046:Gold / Q000737:chemistry*; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry*; D008969:Molecular Sequence Data; D010316:Particle Size; D011485:Protein Binding; D059748:Proteolysis; D013050:Spectrometry, Fluorescence; D014357:Trypsin / Q000378:metabolism; D051844:alpha-Synuclein / Q000737:chemistry* / Q000378:metabolism
chemical_list: D051844:alpha-Synuclein; D006046:Gold; D014357:Trypsin