Figure 1

Left Panel: A lipid bilayer supports the alpha-hemolysin heptamer that creates the pore, or channel, used to collect the data, as shown left. The bilayer is established and supported across an aperture that typically provides 5–25 um in effective bilayer diameter, and generally greater than 1 um. Right Panel: The assembled alpha-Hemolysin pore shown to scale, with a captured dsDNA molecule. As shown, the double stranded form is too wide to pass through the pore, while a single strand may pass through. Bottom Panel: One-second blockade patterns of four DNA hairpins, part of a test set of nine base-pair hairpins, with 4 dT hairpin loops, that have been studied extensively. The molecules only differ in their terminal base-pairs, yet their channel current blockade signals, "signatures", are easily resolved [4].