Simple Electrochemical Method For Detection Research Articles

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

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.

The simple electrochemical method for detection of 3d molecular reorientation in adsorbed layers of organic substances

Reorientation of initially flatly adsorbed molecules to slanted or fully erected positions on the electrode surface seems to be a common transition during adsorption of organic substances. However, the reorientation is not easily detected and its occurrence often questioned. In this paper we present a simple electrochemical method to detect 3d molecular reorientation at the electrode surface. The method is based on the ac voltammetric measurement of the rate of change of the capacitive current, d I c/d t with time, during the adsorption process, which is qualitatively different for adsorption with reorientation in respect of that without it. The theoretical considerations of simple, diffusion-controlled adsorption without reorientation predicts a monotonic decrease of the d I c/d t curve. This is demonstrated experimentally in the adsorption of almost isotropic 1-aminoadamantanehydrochloride. Contrary to this theoretical prediction, it is shown that, in cases where the orientational ordering and reorientation take place, the rate of change of capacitive current vs. time exhibits a plateau followed by steep decrease. Such behavior is demonstrated experimentally in adsorption of the anisotropic, rod-like Triton-X-100 molecule. This has previously been shown to undergo reorientation during the adsorption process. Qualitatively the same behavior of d I c/d t was observed for both molecules in the case of diffusion controlled adsorption as well as adsorption from stirred solution.