Fig. 2.

Zn²⁺ can simultaneously coordinate intra- and intermolecularly, bridging two peptides, consequently promoting aggregation. (A) Model M1, parallel organization, based on the Zirah–Lührs (18, 29) coordinates (Fig. 1). (B) Zn²⁺ (green balls) can coordinate the N terminals of two neighboring peptides: In the yellow N terminal, the intramolecular coordination of Zn is via three His side chains and one Glu. Zn²⁺ in the red N terminal can also form intermolecular coordination with Asp7 in the yellow region via either its backbone carbonyl group or side chain. (C) Averaged distance between the two carboxyl groups of Asp7 and Zn²⁺ during the simulations of M1, indicating that the side chains of Asp7 replace backbone carbonyl group.