The structure of ferritin cores determined by electron nanodiffraction

Electron nanodiffraction, with a 100-keV electron beam less than 1 nm in di ameter, has been used to obtain single-crystal diffraction patterns from in dividual iron-containing cores of ferritin molecules. We show that, while a majority of the cores have a hexagonal structure somewhat similar to the m ajor phase in the mineral ferrihydrite, as previously assumed, several mino r phases are present including some that are similar in structure to the ir on oxides magnetite and hematite and also some composed of highly disordere d material. In general, each core consists of one single crystal of one pha se. (C) 2000 Academic Press.