Hidden Complexity of Synergistic Roles of Dopa and Lysine for Strong Wet Adhesion*

Dopa and lysine are widely found in mussel foot proteins and are suggested to provide synergistic roles for wet adhesion; yet, the detailed molecular mechanism remains unclear. Here, combining single molecule force spectroscopy and ensemble measurements, we found that the neighboring lysine can significantly enhance surface binding of Dopa through three distinct mechanisms: 1) Displacing surface water and ion to increase the effective binding sites; 2) Being directly involved in cooperative surface binding in a sequence dependent manner; 3) Enhancing cohesion by Michael addition to oxidized species or forming cation-p interactions. This study may be helpful for rational design of biomimetic strong adhesives for biomedical applications.