Zn determines amyloid shape

A new spectroscopic study may help researchers get a better handle on how metal-ion coordination dictates the assembly and morphology of amyloid fibrils associated with diseases such as Alzheimer's (J. Am. Chem. Soc., published online March 1, dx.doi.org/10.1021/ja055973j). Transition metals such as zinc previously have been implicated in the assembly of amyloid fibrils. Now, a team led by David G. Lynn of Emory University has shown that Zn²⁺ binding dictates amyloid morphology, too. The researchers report that different Zn²⁺ concentrations force simple segments of the Aβ peptide of Alzheimer's disease to assemble into different morphologies, including fibrils (top) and ribbons (bottom). They used X-ray absorption spectroscopy to show that differences in the metal ion's coordination environment dictate which amyloid architecture is formed. The characteristic spectroscopic signatures they report can now be used to investigate metal coordination in full-length Aβ assemblies. Such information may reveal chemical reactivity important for cellular toxicity of Aβ, they note.