Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Protein adsorption wikipedia , lookup
Molecular evolution wikipedia , lookup
Cell-penetrating peptide wikipedia , lookup
Self-assembling peptide wikipedia , lookup
Peptide synthesis wikipedia , lookup
X-ray crystallography wikipedia , lookup
Proteolysis wikipedia , lookup
Ribosomally synthesized and post-translationally modified peptides wikipedia , lookup
Molecular Mechanisms of Fluorescent Dye Interaction with Flemish Mutation in Amyloid Beta Precursor Protein Stephanie Phuong Le Mentors: James Nowick, Kevin Chen Point mutations in amyloid beta precursor protein (APP) such as the Flemish mutation cause early-onset Alzheimer’s disease. Previous studies found that fibril-like assemblies of amyloid beta proteins can be visualized and quantified using fluorescent dyes such as Thioflavin-T (ThT) and Congo Red. These dyes are widely used, but their molecular mechanisms are unknown. Previous x-ray crystallographic study in the Nowick lab have shown that a macrocyclic peptide model of amyloid-beta’s Flemish mutation (A21G) forms fibril-like assemblies in a crystal lattice; therefore, co-crystallization with ThT and Congo Red may reveal dye binding mechanisms. The macrocyclic peptide model of Flemish mutation was synthesized using solid phase peptide synthesis. Following synthesis and purification, crystals were grown in previously established conditions with ThT and Congo Red as additives. Co-crystallization with Congo Red produced crystals with space group C2221 at 2.4 Å resolution, differing from the Flemish mutation without additive (P212121). ThT co-crystallization had the same space group as the Flemish (P212121 at 2.0 Å resolution). Electron density maps revealed no interaction of the Flemish mutation macrocyclic peptide with ThT. Additionally, partial electron density near the tripeptide mimic, Hao, was observed in the electron density map of the Flemish mutation macrocyclic peptide with Congo Red, indicating hydrophobic interactions. However, due to the poor electron density, the presence of Congo Red in the crystal lattice cannot be concluded. Future studies include crystal optimization to generate better x-ray diffracting crystals.