Plasmin cleaves Abeta42 in vitro and prevents its aggregation into beta-pleated sheet structures.

The formation, aggregation and deposition of amyloid beta peptide (Abeta) is implicated in the aetiology of Alzheimer's disease. Impairment of proteolytic degradation of Abeta may be a key factor in the progression of the disease. We have used RP-HPLC and thioflavin T fluorescence to demonstrate that Abeta42 is rapidly cleaved by the protease plasmin and that cleavage prevented the aggregation of Abeta42, and its cleavage products, into beta-pleated sheet structures. Plasmin may fulfil a similar role in vivo.