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Updated: Jul 3, 2026
Characteristics of Precipitation-formed Polyethylene Glycol Microgels Are Controlled by Molecular Weight of Reactants
Published on: December 23, 2013
Sizing the Bacillus anthracis PA63 channel with nonelectrolyte poly(ethylene glycols)
Brian J Nablo1, Kelly M Halverson, Joseph W F Robertson
1Electrical and Electronics Laboratory, Semiconductor Electronics Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8120, USA.
Abstract:
Nonelectrolyte polymers of poly(ethylene glycol) (PEG) were used to estimate the diameter of the ion channel formed by the Bacillus anthracis protective antigen 63 (PA(63)). Based on the ability of different molecular weight PEGs to partition into the pore and reduce channel conductance, the pore appears to be narrower than the one formed by Staphylococcus aureus alpha-hemolysin. Numerical integration of the PEG sample mass spectra and the channel conductance data were used to refine the estimate of the pore's PEG molecular mass cutoff (approximately 1400 g/mol). The results suggest that the limiting diameter of the PA(63) pore is <2 nm, which is consistent with an all-atom model of the PA(63) channel and previous experiments using large ions.
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