Amyloid beta protein (A beta) from Alzheimer's disease formed fibrillar aggregates and their morphology depended on oxidized and negatively charged liposomes. The morphology of fibrillar aggregates was affected by Cu2+, together with their growth kinetics. This is because Cu2+ inhibited the nucleation step in the formation of amyloid A beta fibrillar aggregates by forming A beta/Cu complex inactive to the growth of fibrillar aggregates. In addition, this is probably because Cu2+ affected the fibrillar aggregate formed on the surface of liposomes. These findings would give a better understanding of the formation mechanism of amyloid fibrils on biomembranes. (C) 2011, The Society for Biotechnology, Japan. All rights reserved.