Unzipping the mysteries of amyloid fiber formation.

I nterest in the phenomenon of protein aggregation is as old as protein research. For example, changes in activity and covalent structure accompanying ‘‘coagulum’’ formation by insulin were important to the elucidation of the molecular origins of hormone action (1). In recent memory, the phenomenon of aggregation served only as an annoyance to the research biochemist and a serious economic consideration in the production and distribution of protein pharmaceuticals. Now, however, one class of aggregate has drawn considerable interest from a range of disciplines. These aggregates are readily identified ultrastructurally by the presence of nonamorphous, filamentous structures, termed amyloid fibers.