Elaine R. Chan1, Brian J. Nablo1, Tam L. Nguyen2, John J. Kasianowicz1, and Vincent M. Stanford3. (1) Semiconductor Electronics Division, Electronics and Electrical Engineering Laboratory, NIST, 100 Bureau Drive, Gaithersburg, MD 20899-8120, (2) Target-Based Drug Discovery Group, SAIC-Frederick, NCI-Frederick, Frederick, MD 21702, (3) Information Access Division, Information Technology Laboratory, NIST, 100 Bureau Drive, Gaithersburg, MD 20899-8940
Determining the detailed structure of the ion channel formed by anthrax protective antigen 63 should help determine the toxin's mechanism of action. Although a crystallographic structure of the nanopore is not yet available, a model for the channel has been proposed. To test the model, we are measuring the single channel current-voltage relationships in the presence of 1:1 monovalent electrolyte solutions and under various electrolyte concentration and pH conditions. Advanced statistical signal processing algorithms are applied to the stochastic fluctuations in the single channel ionic current time series to determine the number, value, and lifetimes of all the conductance states. The results may also prove useful for developing therapeutic agents against anthrax.