title: Sizing the Bacillus anthracis PA63 channel with nonelectrolyte poly(ethylene glycols).
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.
authors.affiliation: Electrical and Electronics Laboratory, Semiconductor Electronics Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8120, USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Nablo
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Halverson
authors.forename: Joseph W F
authors.initials: JW
authors.lastname: Robertson
authors.forename: Tam L
authors.initials: TL
authors.lastname: Nguyen
authors.forename: Rekha G
authors.initials: RG
authors.lastname: Panchal
authors.forename: Rick
authors.initials: R
authors.lastname: Gussio
authors.forename: Sina
authors.initials: S
authors.lastname: Bavari
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Krasilnikov
authors.forename: John J
authors.initials: JJ
authors.lastname: Kasianowicz
mesh_terms: D000942:Antigens, Bacterial / Q000737:chemistry* / Q000648:ultrastructure*; D001408:Bacillus anthracis / Q000737:chemistry*; D001427:Bacterial Toxins / Q000737:chemistry*; D003198:Computer Simulation; D004573:Electrolytes / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D011092:Polyethylene Glycols / Q000737:chemistry*; D016062:Porosity; D011487:Protein Conformation
chemical_list: D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D004573:Electrolytes; C030325:anthrax toxin; D011092:Polyethylene Glycols