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Size-dependent forced PEG partitioning into channels: VDAC, OmpC, and α-hemolysin
M Alphan Aksoyoglu1, Rudolf Podgornik2, Sergey M Bezrukov3
1Department of Physics, University of Massachusetts, Amherst, MA 01003;
Summary
Nonideal polymer mixtures partition into protein channels. A new theory shows less-penetrating polymers can force more-penetrating polymers into channels, explaining polymer partitioning in nanopores.
Area of Science:
- Biophysics
- Polymer Science
- Nanotechnology
Background:
- Nonideal polymer mixtures, such as polyethylene glycols (PEGs) of varying molecular weights, exhibit differential partitioning behavior within nanosize protein channels.
- Understanding this partitioning is crucial for applications involving selective molecular transport and separation.
Purpose of the Study:
- To evaluate the applicability of the forced partitioning theory to three distinct β-barrel protein channels.
- To analyze polymer partitioning dynamics within these nanopores.
Main Methods:
- Experimental assessment of polymer partitioning in three protein channels: VDAC, OmpC, and α-hemolysin.
- Comparison of experimental data with the theoretical framework of forced partitioning.
Main Results:
- Excellent agreement between theory and experiments was observed for the voltage-dependent anion channel (VDAC).
- For bacterial porin OmpC and α-hemolysin, experimental data aligned with the theory when accounting for pore penetration energy penalties.
- The 'polymers pushing polymers' concept effectively explains size-dependent forced partitioning.
Conclusions:
- The forced partitioning theory provides a valuable framework for understanding polymer behavior in protein nanopores.
- The 'polymers pushing polymers' phenomenon is a key factor in size-dependent polymer partitioning.
- This study validates and refines the application of forced partitioning theory across different protein channel architectures.
