Random and Alternating Polyampholytes

We discuss theoretically the influence of the distribution of the charged monomers on the conformational properties of polyampholyte chains using the random phase approximation. If the distribution is quenched with random positions of the positive and negative charges, the polyampholyte collapses and locally has the same structure as a salt solution. It can be described by the Debye-Hückel theory. If the charges are alternating, the collapsed chain is a dielectric medium that can be characterized by a finite negative virial coefficient. Alternating polyampholytes are more soluble than random polyampholytes. We also study intermediate distributions and the annealed problem where the charges are due to the dissociation of acidic and basic monomers.