Electrocatalytic Currents from Single Enzyme Molecules

Abstract

Single molecule enzymology provides an opportunity to examine details of enzyme mechanisms that are not distinguishable in biomolecule ensemble studies. Here we report, for the first time, detection of the current produced in an electrocatalytic reaction by a single redox enzyme molecule when it collides with an ultramicroelectrode. The catalytic process provides amplification of the current from electron-transfer events at the catalyst leading to a measurable current. This new methodology monitors turnover of a single enzyme molecule. The methodology might complement existing single molecule techniques, giving further insights into enzymatic mechanisms and filling the gap between fundamental understanding of biocatalytic processes and their potential for bioenergy production.

Unveiling the Intrinsic Catalytic Activities of Single‐Gold‐Nanoparticle‐Based Enzyme Mimetics

“…In this work, single AuNPs exhibited hundreds-or even thousands-fold enhancement of GOx-mimicking activity compared with the previously obtained results based on the averaged ensemble measurements, [20,[44][45][46][47] which was consistent with the catalytic kinetics of afree diffusing single enzyme with high TONusing singleentity electrochemical measurements. [29,42,43] Significantly enhanced catalytic activity can be best explained by considering the high accessible surface area of monodispersed AuNPs in our measurement. [40,41] Moreover,c arbon as the support can develop different interactions with AuNPs during their collision processes at aC UME surface,t hus modifying both the electronic and structural properties of AuNPs.…”

“…[23,26] Despite ongoing progress in the development of these artificial catalytic systems,q uantifying the intrinsic structure-activity relationships remains challenging due to the average effect of traditional ensemble measurements. [28][29][30][31] To screen for the optimal nanocatalysts,the same conditions need to be used for screening all candidate nanocatalysts. [28][29][30][31] To screen for the optimal nanocatalysts,the same conditions need to be used for screening all candidate nanocatalysts.…”

Measuring the oxygen content of a single oil droplet

“…9–11 Starting with the work of Hellberg et al where lecithin liposomes were recorded through capacitative ‘spikes’, 12 recently, this method was extended by our group and others to detect “soft” nanoparticles including micelles, 13 liposomes, 14 droplets, 15–18 vesicles, 19,20 and, it is claimed, enzymes. 21 …”

Reply to Comment on “Can Nanoimpacts Detect Single-Enzyme Activity? Theoretical Considerations and an Experimental Study of Catalase Impacts”

“…On the other hand, there might be reaction via the so-called direct electron transfer, which is represented by either eq 2 ± ′ → ″ − ES n P e (2) or eq 3…”