Peptide Length and Dopa Determine Iron-Mediated Cohesion of Mussel Foot Proteins

• Published in: Advanced functional materials 2015-09, Vol.25 (36), p.5840-5847
• Main Authors: Das, Saurabh, Rodriguez, Nadine R. Martinez, Wei, Wei, Waite, J. Herbert, Israelachvili, Jacob N.
• Format: Article
• Language: English
• Subjects: Adhesion; Bridging; Cations; coating proteins; Cohesion; Dopa; Fe chelation; mfp-1 peptide; Mica; mussel foot protein; Mussels; Peptides; Proteins
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201502256

Mussel adhesion to mineral surfaces is widely attributed to 3,4‐dihydroxyphenylalanine (Dopa) functionalities in the mussel foot proteins (mfps). Several mfps, however, show a broad range (30%–100%) of tyrosine (Tyr) to Dopa conversion suggesting that Dopa is not the only desirable outcome for adhesion. Here, a partial recombinant construct of mussel foot protein‐1 (rmfp‐1) and short decapeptide dimers with and without Dopa are used and both their cohesive and adhesive properties on mica are assessed using a surface forces apparatus. Our results demonstrate that at low pH, both the unmodified and Dopa‐containing rmfp‐1s show similar energies for adhesion to mica and self–self‐interaction. Cohesion between two Dopa‐containing rmfp‐1 surfaces can be doubled by Fe3+ chelation, but remains unchanged with unmodified rmfp‐1. At the same low pH, the Dopa‐modified short decapeptide dimer did not show any change in cohesive interactions even with Fe3+. The results suggest that the most probable intermolecular interactions are those arising from electrostatic (i.e., cation–π) and hydrophobic interactions. It is also shown that Dopa in a peptide sequence does not by itself mediate Fe3+ bridging interactions between peptide films: peptide length is a crucial enabling factor. Fe3+‐mediated bridging of the mussel foot proteins (mfps) is attributed to two equally influential parameters: peptide architecture and 3,4‐dihydroxyphenyl­alanine (Dopa) residues in the protein. In addition, serial “hydrogen bonding” and cation–π interactions between the aromatic residues in the protein and a mineral surface are more probable than bidentate H‐bonding interactions in adhering mfps to the surface.