Papers by Keyword: Prion Protein

Abstract: Prion protein has drawn great attention due to its pathological potential to prion diseases. Discriminate and detection of the trace quantities PrP^Sc is an important measure for prion disease diagnosis at the presymptomatic stage. In this study, we developed a novel sandwich surface plasmon resonance (SPR) assay for the detection of PrP^Sc, involving bare gold surfaces and bare gold nanoparticles. PrP^Sc can be captured by the SPR sensing surface via a surface assisted coupling reaction between its intra-molecular disulfide bond and the gold atoms, while PrP^C cannot bind to the gold surface strongly. The gold nanoparticles were proved to amplify the SPR detection signals via the coupling of their localized surface plasmon (LSP) with the propagating plasmon on the SPR gold surface. Our results confirmed that the bare SPR gold surface successfully captured the PrP^Sc from the solution with a LOD of 0.5ng/mL and a linear detection range from 0.5ng/mL to 500ng/mL. Injecting the gold nanoparticles after PrP^Sc yielded a dramatic enhancement of signal, with a lower LOD of 0.001ng/mL and a linear detection range from 0.001ng/mL to 10ng/mL. The gold nanoparticles permitted 4 to 322-fold increase of the signals. The required detection time was controlled in 15 min. PrP^C, cys-protein G and their mixtures with PrP^Sc, were also detected via this sandwich SPR detection assay. Atomic force microscope (AFM) was used to evaluate the surface morphology of the SPR gold substrate after the detection. All the obtained results suggested that this novel SPR sandwich detection assay in our work was efficient, sensitive and specific for the detection of trace PrP^Sc

Abstract: Amyloid fibrils have long been established as the well-known a-helix to b-sheet transition that characterizes the conversion of the cellular form of prion proteins into a scrapie form. A very short sequence of the Yeast prion-like protein GNNQQNY(SupN) is responsible for the aggregation that induces diseases. As such, in the current study, a GST-fused monomer SupN vector is used to express the SupN peptide in Escherichia coli(E. Coli). In addition, a method for the production, purification, and cleavage of the recombinant SupN in E. coli is also described, which yields as much as 2mg per liter of growth of natural abundance fusion proteins in LB media. To gain a better understanding of the aggregation-structure relationship of the 7 residues of the Yeast prion-like protein, the change in the conformational structure is studied by Transmission Electron Microscopy and will be further studied by 13C solid-state NMR. Accordingly, this is the first investigation of the fibril formation of a heptamer peptide expressed in E.coli.