Counting polymers moving through a single ion channel.

S M Bezrukov; I Vodyanoy; V A Parsegian

doi:10.1038/370279a0

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Counting polymers moving through a single ion channel.

S M Bezrukov·I Vodyanoy·V A Parsegian

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Abstract

The change in conductance of a small electrolyte-filled capillary owing to the passage of sub-micrometre-sized particles has long been used for particle counting and sizing. A commercial device for such measurements, the Coulter counter, is able to detect particles of sizes down to several tenths of a micrometre. Nuclepore technology (in which pores are etched particle tracks) has extended the lower limit of size detection to 60-nm particles by using a capillary of diameter 0.45 micron (ref. 4). Here we show that natural channel-forming peptides incorporated into a bilayer lipid membrane can be used to detect the passage of single molecules with gyration radii as small as 5-15 A. From our experiments with alamethicin pores we infer both the average number and the diffusion coefficients of poly(ethylene glycol) molecules in the pore. Our approach provides a means of observing the statistics and mechanics of flexible polymers moving within the confines of precisely defined single-molecule structures.

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Alamethicin Diffusion Ion Channels Lipid Bilayers Particle Size Polymers Journal Article Research Support, U.S. Gov't, Non-P.H.S.

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S M Bezrukov, I Vodyanoy, V A Parsegian. 1994-07-28. Counting polymers moving through a single ion channel.. https://doi.org/10.1038/370279a0

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