Figure 7.

Negatively charged random coils mediate salt-induced transitioning from a flexible to a defined structure. A) In the absence of salt, the polymerase experiences dynamic structural fluctuations as a result of its increased percentage of random coils. Excess negative charges (Asp and Glu) on the surface and/or on the random coils mediate this flexibility through repulsive forces. B) In the presence of salt, the binding of hydrated Na⁺ ions to acidic residues stabilizes the random coils and reduces the dynamic structural fluctuations leading to the formation of a more functional conformer.