Estimation of Shape, Volume, and Dipole Moment of Individual Proteins Freely Transiting a Synthetic Nanopore.

Authors:
Jared Houghtaling
Jared Houghtaling
University of Washington
Seattle | United States
Cuifeng Ying
Cuifeng Ying
Chongqing Key Laboratory of Multi-scale Manufacturing Technology
Olivia M Eggenberger
Olivia M Eggenberger
Adolphe Merkle Institute
Aziz Fennouri
Aziz Fennouri
Université d'Evry Val d'Essonne
France
Jiali Li
Jiali Li
University of Arkansas
United States
Adam R Hall
Adam R Hall
Kavli Institute of Nanoscience
Netherlands

ACS Nano 2019 May 24;13(5):5231-5242. Epub 2019 Apr 24.

Adolphe Merkle Insitute, University of Fribourg , CH-1700 Fribourg , Switzerland.

This paper demonstrates that high-bandwidth current recordings in combination with low-noise silicon nitride nanopores make it possible to determine the molecular volume, approximate shape, and dipole moment of single native proteins in solution without the need for labeling, tethering, or other chemical modifications of these proteins. The analysis is based on current modulations caused by the translation and rotation of single proteins through a uniform electric field inside of a nanopore. We applied this technique to nine proteins and show that the measured protein parameters agree well with reference values but only if the nanopore walls were coated with a nonstick fluid lipid bilayer. One potential challenge with this approach is that an untethered protein is able to diffuse laterally while transiting a nanopore, which generates increasingly asymmetric disruptions in the electric field as it approaches the nanopore walls. These "off-axis" effects add an additional noise-like element to the electrical recordings, which can be exacerbated by nonspecific interactions with pore walls that are not coated by a fluid lipid bilayer. We performed finite element simulations to quantify the influence of these effects on subsequent analyses. Examining the size, approximate shape, and dipole moment of unperturbed, native proteins in aqueous solution on a single-molecule level in real time while they translocate through a nanopore may enable applications such as identifying or characterizing proteins in a mixture, or monitoring the assembly or disassembly of transient protein complexes based on their shape, volume, or dipole moment.

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Source
http://pubs.acs.org/doi/10.1021/acsnano.8b09555
Publisher Site
http://dx.doi.org/10.1021/acsnano.8b09555DOI Listing
May 2019
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