A designed apoplastocyanin variant that shows reversible folding

Plastocyanin, like many other metalloproteins, does not undergo reversible folding, which is thought to be due to an irreversible conformational change in the copper-binding site. Moreover, apoplastocyanin's ability to adopt a native tertiary structure is highly salt-dependent, and even in high salt, it has an irreversible thermal denaturation. Here, we report a designed apoplastocyanin variant, PCV, that is well folded and has reversible folding in both high and low salt conditions. This variant provides a tractable model for understanding and designing protein β-sheets.