title: Complexation between Cu(II) and curcumin in the presence of two different segments of amyloid β.
abstract: The natural product curcumin has been shown to play a role in preventing Aβ amyloid fibril formation. This role could include chelation of transition metal ions such as Cu(2+), known to accelerate amyloid aggregation, and/or curcumin-binding directly to the Aβ protein. To investigate these different roles, curcumin complexation to Cu(2+) was investigated in the presence and absence of two different segments of the Aβ protein including the copper-binding (Aβ6-14) and curcumin-binding (Aβ14-23) domains. Absorbance and fluorescence spectroscopy in 90% water/10% methanol solutions showed that curcumin can bind Cu(2+) to some extent in the presence of both segments despite strong peptide-ion interactions. Estimated Cu(2+)-curcumin binding affinities in the absence (1.6×10(5)M(-1)) and presence (7.9×10(4)M(-1)) of the peptide provide quantitative support for this Cu(2+) chelation role. With the Aβ14-23 segment, the curcumin simultaneously binds to Cu(2+) and the peptide, demonstrating that it can play multiple roles in the prevention of amyloid formation. The stabilities of ternary peptide-Cu(2+)-curcumin complexes were evaluated using ESI mass spectrometry and support the conclusion that curcumin can act as a weak metal ion chelator and also bind directly to the Aβ14-23 peptide segment.
authors.affiliation: Department of Chemistry and Biochemistry, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028, USA.
authors.forename: Angela L
authors.initials: AL
authors.lastname: Picciano
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Vaden
mesh_terms: D016229:Amyloid beta-Peptides / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D003474:Curcumin / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D016229:Amyloid beta-Peptides; D003300:Copper; D003474:Curcumin
keywords: Amyloid–metal ion binding; Chelation drug; Curcumin; Fluorescence spectroscopy; Mass spectrometry; Peptide