title: Adhesion mechanism in a DOPA-deficient foot protein from green mussels().
abstract: The holdfast or byssus of Asian green mussels, Perna viridis, contains a foot protein, pvfp-1, that differs in two respects from all other known adhesive mussel foot proteins (mfp): (1) instead of the hallmark L-3,4-dihydroxyphenylalanine (DOPA) residues in mfp-1, for example, pvfp-1 contains C(2)-mannosyl-7-hydroxytryptophan (Man7OHTrp). (2) In addition, pvfp-1 chains are not monomeric like mfp-1 but trimerized by collagen and coiled-coil domains near the carboxy terminus after a typical domain of tandemly repeated decapeptides. Here, the contribution of these peculiarities to adhesion was examined using a surface forces apparatus (SFA). Unlike previously studied mfp-1s, pvfp-1 showed significant adhesion to mica and, in symmetric pvfp-1 films, substantial cohesive interactions were present at pH 5.5. The role of Man7OHTrp in adhesion is not clear, and a DOPA-like role for Man7OHTrp in metal complexation (e.g., Cu(2+), Fe(3+)) was not observed. Instead, cation-π interactions with low desolvation penalty between Man7OHTrp and lysyl side chains and conformational changes (raveling and unraveling of collagen helix and coiled-coil domains) are the best explanations for the strong adhesion between pvfp-1 monomolecular films. The strong adhesion mechanism induced by cation-π interactions and conformational changes in pvfp-1 provides new insights for the development of biomimetic underwater adhesives.
authors.affiliation: Ocean Science and Technology Institute, Pohang University of Science and Technology, Hyoja-Dong, Nam-Gu, Pohang, Gyeongbuk, 790-784, Korea ; Materials Research Laboratory, University of California, Santa Barbara, CA 93106, USA.
authors.forename: Dong Soo
authors.initials: DS
authors.lastname: Hwang
authors.forename: Hongbo
authors.initials: H
authors.lastname: Zeng
authors.forename: Qingye
authors.initials: Q
authors.lastname: Lu
authors.forename: Jacob
authors.initials: J
authors.lastname: Israelachvili
authors.forename: J Herbert
authors.initials: JH
authors.lastname: Waite