A simple and label-free electrochemical method for detection of beta-site amyloid precursor protein cleaving enzyme and screening of its inhibitor

Abstract

Beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) is an aspartic protease that promotes the production of beta-amyloid (Aβ) peptides from beta-site amyloid precursor protein. Pharmacological reduction of Aβ production by inhibiting BACE1 has emerged as a promising target for the treatment of Alzheimer's disease (AD). In this work, we reported a simple electrochemical method for detection of BACE1 and screening of its inhibitor. This method made use of an unlabeled peptide that comprises a segment of beta-site amyloid precursor protein with the Swiss mutation. The peptide–heme complex formed on the electrode surface showed strong electrocatalytic O2 reduction. Cleavage of the peptide by BACE1 detached the heme-binding fragment from the electrode surface, leading to a remarkable decrease in the electrochemical signal. Suppression of BACE1 by the inhibitor yielded a larger voltammetric signal. The IC50 of the inhibitor tested by this method (15.7nM) was in agreement with that reported. The proposed method could serve as a promising alternative to the traditional methods for probing of BACE1 activity and screening of BACE1 inhibitor owing to its simplicity, high sensitivity and low assay cost.