Change of colloidal and surface properties of Mytilus edulis foot protein 1 in the presence of an oxidation (NaIO4) or a complex-binding (Cu2+) agent.
Quartz crystal microbalance with dissipation monitoring (QCM-D) was used to study the viscoelastic properties of the blue mussel, Mytilus edulis, foot protein 1 (Mefp-1) adsorbed on modified hydrophobic gold surfaces. The change in viscoelasticity was studied after addition of Cu2+ and Mn2+, which theoretically could induce metal complex formation with 3,4-dihydroxyphenylalanine (DOPA) moieties. We also used NaIO4, a nonmetal oxidative agent known to induce di-DOPA formation. Reduction in viscoelasticity of adsorbed Mefp-1 followed the order of NaIO4 > Cu2+ > buffer control > Mn2+. We also studied the formation of molecular aggregates of Mefp-1 in solution with the use of dynamic light scattering (DLS). We found that addition of Cu2+, but not Mn2+, induced the formation of larger DLS-detectable aggregates. Minor aggregate formation was found with NaIO4. With the analytical resolution of small angle X-ray scattering (SAXS), we could detect differences in the molecular structure between NaIO4- and Cu2+-treated Mefp-1 aggregates. We concluded from this study that Cu2+ could participate in intermolecular cross-linking of the Mefp-1 molecule via metal complex formation. Metal incorporation in the protein most likely increases the abrasion resistance of the Mefp-1 layer. NaIO4, on the other hand, resulted in mainly intramolecular formation of di-DOPA, but failed to induce larger intermolecular aggregation phenomena. The described methodological combination of surface sensitive methods, like QCM-D, and bulk sensitive methods, like DLS and SAXS, generates high resolution results and is an attractive platform to investigate intra- and intermolecular aspects of assembly and cross-linking of the Mefp proteins.
Hedlund
J
J
Department of Cell and Molecular Biology, Interface Biophysics, Göteborg University, Box 462, 405 30 Göteborg, Sweden.
Andersson
M
M
Fant
C
C
Bitton
R
R
Bianco-Peled
H
H
Elwing
H
H
Berglin
M
M
D000818:Animals; D002712:Chlorides / Q000494:pharmacology; D003300:Copper / Q000494:pharmacology*; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004295:Dihydroxyphenylalanine / Q000737:chemistry; D017979:Gold Colloid / Q000737:chemistry; D017895:Manganese Compounds / Q000494:pharmacology; D008934:Mitogens / Q000494:pharmacology*; D049880:Mytilus edulis / Q000737:chemistry*; D010084:Oxidation-Reduction; D010504:Periodic Acid / Q000494:pharmacology*; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D013499:Surface Properties; D014783:Viscosity; D014965:X-Rays
D002712:Chlorides; D003432:Cross-Linking Reagents; D017979:Gold Colloid; D017895:Manganese Compounds; D008934:Mitogens; D011506:Proteins; C037403:adhesive protein, mussel; D010504:Periodic Acid; D004295:Dihydroxyphenylalanine; D003300:Copper; C009288:metaperiodate; C028419:cuprous chloride; C025340:manganese chloride