Microscale Crystals of Cytochrome <i>c</i> and Calixarene on Electrodes: Interprotein Electron Transfer between Defined Sites

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.

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“…Interestingly, recent studies have shown that in calixarene-supported cyt c crystals ET between fixed redox sites is feasible. 54 …”

Section: Resultsmentioning

confidence: 99%

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

et al. 2016

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“…Examples include the use of calixarenes, cucurbiturils, foldamers, and fullerene (C 60 ) . The water‐soluble p ‐sulfonatocalix[4]arene (sclx 4 ) is a versatile receptor for cationic side chains and serves as molecular glue for protein assembly –. Previously, it was shown by X‐ray crystallography that three sclx 4 molecules bind to different lysines on cytochrome c (cyt c ) .…”

Section: Figurementioning

confidence: 99%

Protein Dimerization on a Phosphonated Calix[6]arene Disc

et al. 2017

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Complex formation between cationic cytochrome c and the water‐soluble, poly‐anionic p‐phosphonatocalix[6]arene (pclx6) was investigated. A crystal structure (at 1.8 Å resolution) revealed a remarkable dimeric disc of pclx6 that acts like glue to mediate a symmetric (C2) protein dimer. The calixarene disc has a diameter of about 1.5 nm and masks about 360 Å2 of protein surface. The key protein–calixarene contacts occur via two linchpin lysines, with additional contacts provided by a small hydrophobic patch. The protein–calixarene supramolecular assemblies were observed in solution by size‐exclusion chromatography with multi‐angle light scattering and NMR spectroscopy. Using isothermal titration calorimetry and NMR data, an apparent Kd in the low micromolar range was determined for the charge‐rich protein–calixarene complex. In contrast to p‐sulfonatocalix[4]arene, the larger pclx6 has a single, well‐defined binding site that mediates the assembly of cytochrome c in solution.

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“…The regulation of protein assembly and disassembly mediated by soluble derivatives and based on rational supramolecular approaches has known a growing interest the last decades. 1,2 Indeed, these molecular glues, such as lanthanide coordination complex 3,4 , polyoxometalate clusters 5,6 or organic supramolecular compounds, [7][8][9][10][11] favor protein/additive/protein adduct to create protein material 12 or induce protein crystallization. 13 In that realm, functionalized calixarenes, notably para-sulfonato-calix-[n]-arenes have demonstrated their high potential in biochemistry thanks to their abilities to bind positively charged protein surface to form protein oligomers.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics approach for capturing calixarenes--proteins interactions: the case of cytochrome c

Bartocci¹,

szczepaniak²,

Jiang³

et al. 2020

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Here, we propose a molecular dynamics investigation of the supramolecular association of sulfonatedcalix-[8]-arenes to cytochrome c. The binding sites prone to interactions with sulfonated calixarenescan be identified without prior knowledge of the X-ray structure, and the binding free energiesestimated by molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) post-analysis arefound to be in neat agreement with the isothermal titration calorimetry (ITC) measurements The per-residuedecomposition reveals the detailed picture of this electrostatically-driven association and notably therole of the arginine R13 as a bridge residue between the two main anchoring sites. In addition,the analysis of the residue behavior by means of a supervised machine learning protocol unveils the formation of an hydrogen bond network far from the binding sites, increasing the rigidity of theprotein.

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Microscale Crystals of Cytochrome c and Calixarene on Electrodes: Interprotein Electron Transfer between Defined Sites

Cited by 41 publications

References 26 publications

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

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

Protein Dimerization on a Phosphonated Calix[6]arene Disc

Molecular dynamics approach for capturing calixarenes--proteins interactions: the case of cytochrome c

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