Evaluation of superior BACE1 cleavage sequences containing unnatural amino acids

Abstract A recombinant form of BACE1 (β-site amyloid precursor protein cleaving enzyme-1) corresponding to positions 46–454 of the extracellular domain of the original membrane enzyme was prepared. The recombinant BACE1 (rBACE1) had the kinetic parameters K m  = 5.5 μM and k cat  = 1719 s −1 . Using several libraries of substrates containing unnatural amino acids, the specificity of rBACE1 was evaluated. LC/MS of digests derived from the libraries clarified that a dodecapeptide containing unnatural amino acids at P 2 to P 1 ′ was a superior cleavage sequence.