Figure 1.

A schematic illustration of the extension of the Betterton and Jülicher model for helicases. The position of the helicase (black circle) on an underlying one-dimensional lattice representing the nucleic acid substrate is denoted by the variable n, while the variable m refers to the location of the ss-dsNA junction. At infinite separation between the helicase and ss-ds NA junction, n → n + 1 transitions occur at rate k⁺, while n → n − 1 transitions occur at rate k⁻. Similarly, m → m + 1 transitions occur at rate α, and m → m − 1 transitions occur at rate β. The tension F is applied to the ends of the nucleic acid. To see this figure in color, go online.