Insights into Interprotein Electron Transfer of Human Cytochrome c Variants Arranged in Multilayer Architectures by Means of an Artificial Silica Nanoparticle Matrix

Abstract

The redox behavior of proteins plays a crucial part in the design of bioelectronic systems. We have demonstrated several functional systems exploiting the electron exchange properties of the redox protein cytochrome c (cyt c) in combination with enzymes and photoactive proteins. The operation is based on an effective reaction at modified electrodes but also to a large extent on the capability of self-exchange between cyt c molecules in a surface-fixed state. In this context, different variants of human cyt c have been examined here with respect to an altered heterogeneous electron transfer (ET) rate in a monolayer on electrodes as well as an enhanced self-exchange rate while being incorporated in multilayer architectures. For this purpose, mutants of the wild-type (WT) protein have been prepared to change the chemical nature of the surface contact area near the heme edge. The structural integrity of the variants has been verified by NMR and UV–vis measurements. It is shown that the single-point mutations can significantly influence the heterogeneous ET rate at thiol-modified gold electrodes and that electroactive protein/silica nanoparticle multilayers can be constructed with all forms of human cyt c prepared. The kinetic behavior of electron exchange for the mutant proteins in comparison with that of the WT has been found altered in some multilayer arrangements. Higher self-exchange rates have been found for K79A. The results demonstrate that the position of the introduced change in the charge situation of cyt c has a profound influence on the exchange behavior. In addition, the behavior of the cyt c variants in assembled multilayers is found to be rather similar to the situation of cyt c self-exchange in solution verified by NMR.

A precursor-approach in constructing 3D ITO electrodes for the improved performance of photosystem I-cyt c photobioelectrodes

“…It has to be mentioned here that this concept also includes the possibility of cyt c -cyt c selfexchange and thus, multiple molecules of the redox protein are involved in the electron delivery from the electrode to PSI and also from the enzyme to PSI. 85,360 With these functional bio-compounds in the mesoporous electrode we are able to transfer their function into a bio-electronic circuit, whereby the different reactions can be attributed to the following electronic elements: the trigger (sulfite), the detector (electrode), the relay network, which also works as a Nernstian capacitor (cyt c) and the photodiode (PSI). The principle including the reaction pathways is illustrated in Fig.…”

Bioelectronic Circuit on a 3D Electrode Architecture: Enzymatic Catalysis Interconnected with Photosystem I

“…It has to be mentioned here that this concept also includes the possibility of cyt c -cyt c self-exchange, and thus multiple molecules of the redox protein are involved in the electron delivery from the electrode to PSI and also from the enzyme to PSI. , …”

Design of a Novel Green Algae‐Based Biological Photovoltaic Cell with High Photocurrent and a Photoelectrochemical Biosensing Approach Utilizing the BPV for Pesticide Analysis in Water

“…On the other hand, the AuE/P(SNS-NH 2 )/Cyt C/Green Algae, indicated the sufficient oxidation and reduction peaks mean that Cyt C and green algae molecules are cross-linked and well-oriented in this structure. [35] In cyclic voltammetry experiments, a 3-electrode cell setup was used at a scan rate of 100 mV/s, if not stated otherwise. All measurements were performed at room temperature (20 � 2 °C).…”

“…Formation of the layers has negative effects on the redox potentials of Cyt C, which shows the blocking of the electrical contact with the electrode. On the other hand, the AuE/P(SNS‐NH 2 )/Cyt C/Green Algae, indicated the sufficient oxidation and reduction peaks mean that Cyt C and green algae molecules are cross‐linked and well‐oriented in this structure [35] . In cyclic voltammetry experiments, a 3‐electrode cell setup was used at a scan rate of 100 mV/s, if not stated otherwise.…”