Figure 7.

Scheme of the cross-linking modes in the hydrogel. In the absence of metal ions, only single coiled coil (CC) cross-links form. At 1:20 Zn²⁺:His, the hydrogel is cross-linked by a mixture of single CCs and small Zn²⁺ cross-linked aggregates. At 1:1 Zn²⁺:His most of the CC-forming peptides participate in these aggregates. The formation of Zn²⁺ cross-linked aggregates is fully reversible when EDTA is added.