title: Size-dependent forced PEG partitioning into channels: VDAC, OmpC, and α-hemolysin.
abstract: Nonideal polymer mixtures of PEGs of different molecular weights partition differently into nanosize protein channels. Here, we assess the validity of the recently proposed theoretical approach of forced partitioning for three structurally different β-barrel channels: voltage-dependent anion channel from outer mitochondrial membrane VDAC, bacterial porin OmpC (outer membrane protein C), and bacterial channel-forming toxin α-hemolysin. Our interpretation is based on the idea that relatively less-penetrating polymers push the more easily penetrating ones into nanosize channels in excess of their bath concentration. Comparison of the theory with experiments is excellent for VDAC. Polymer partitioning data for the other two channels are consistent with theory if additional assumptions regarding the energy penalty of pore penetration are included. The obtained results demonstrate that the general concept of "polymers pushing polymers" is helpful in understanding and quantification of concrete examples of size-dependent forced partitioning of polymers into protein nanopores.
authors.affiliation: Department of Physics, University of Massachusetts, Amherst, MA 01003;
authors.forename: M Alphan
authors.initials: MA
authors.lastname: Aksoyoglu
authors.affiliation: Department of Physics, University of Massachusetts, Amherst, MA 01003; Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia; Department of Theoretical Physics, J. Stefan Institute, 1000 Ljubljana, Slovenia; rudolf.podgornik@ijs.si bezrukos@mail.nih.gov.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Podgornik
authors.affiliation: Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892; rudolf.podgornik@ijs.si bezrukos@mail.nih.gov.
authors.forename: Sergey M
authors.initials: SM
authors.lastname: Bezrukov
authors.affiliation: Department of Physics, University of Massachusetts, Amherst, MA 01003; Section on Molecular Transport, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892;
authors.forename: Philip A
authors.initials: PA
authors.lastname: Gurnev
authors.affiliation: Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003.
authors.forename: Murugappan
authors.initials: M
authors.lastname: Muthukumar
authors.affiliation: Department of Physics, University of Massachusetts, Amherst, MA 01003;
authors.forename: V Adrian
authors.initials: VA
authors.lastname: Parsegian
mesh_terms: D001427:Bacterial Toxins / Q000737:chemistry*; D004573:Electrolytes / Q000737:chemistry; D006460:Hemolysin Proteins / Q000737:chemistry*; D009997:Osmotic Pressure; D011092:Polyethylene Glycols; D018272:Porins / Q000737:chemistry*; D050994:Voltage-Dependent Anion Channels / Q000737:chemistry*
chemical_list: D001427:Bacterial Toxins; D004573:Electrolytes; D006460:Hemolysin Proteins; C113724:OmpC protein; D018272:Porins; D050994:Voltage-Dependent Anion Channels; C021091:staphylococcal alpha-toxin; D011092:Polyethylene Glycols
keywords: macromolecular crowding; nanopore-based sensing; polymer confinement; polymer transport; β-barrel pores