Freezing of a fish antifreeze protein results in amyloid fibril formation

Amyloid is associated with a number of diseases including Alzheimer's, Huntington's, Parkinson's, and the spongiform encephalopathies. Amyloid fibrils have been formed in vitro from both disease and nondisease related proteins, but the latter requires extremes of pH, heat, or the presence of a chaotropic agent. We show, using fluorescence spectroscopy, electron microscopy, and solid-state NMR spectroscopy, that the alpha-helical type I antifreeze protein from the winter flounder forms amyloid fibrils at pH 4 and 7 upon freezing and thawing. Our results demonstrate that the freezing of some proteins may accelerate the formation of amyloid fibrils.