Aβ Produced as a Fusion to Maltose Binding Protein Can Be Readily Purified and Stably Associates with Copper and Zinc

The 42 amino acid Alzheimer's Aβ peptide has been produced in E. coli as a soluble fusion to maltose binding protein (MBP). Affinity purification on amylose columns of MBP-Aβ and MBP led to the recovery of proteins at purities that were suited for physicochemical analyses. MBP-Aβ was able to bind approximately 2 mole equivalents of copper or 4 mole equivalents of zinc, while MBP alone bound negligible amounts of zinc or copper. We conclude that A can bind 2 copper or 4 zinc ions in its fusion format. Because MBP-Aβ is a convenient protein to work with, this system is well suited for further studies on the structure of Aβ and its interactions with metals.