Mussels bind to virtually all types materials through formation of so-called byssus threads. The threads function as an adhesive that is capable of binding even to low energy surfaces such as wax or Teflon. The protein based adhesive has an unusual ability to replace water from a surface which results in the ability to adhere to surfaces as well as to cure in a wet environment.

Biopolymer Products AB has a patent protected production method of Mussel Adhesive Protein (MAP) which is one of the major components in the part of the byssus thread which is called plaque (Figure 1). In scientific literature MAP from Blue Mussel is called MEFP-1, named after the species Mytilus edulis followed by foot protein 1, which indicates that MEFP-1 is the first isolated and characterized foot protein from blue mussel.

The adhesive proteins from different marine mussel species are closely related. Since the eighties, Professor Herbert J. Waite have been isolating and characterizing a number of proteins from the byssus thread as well as proteins from other marine organisms.

MEFP-1, which is the most extensively investigated protein from the mussel byssus, has a molecular weight of 110 000 g/mol. The protein consists of repeating decapeptide units that are repeated 80-85 times (Figure 2). The decapeptide consists primarily of polar and basic amino acids and is positively charged in seawater. The most important amino acid in the protein is 3,4-dihydroxyphenylalanine (DOPA), which is important for the ability to replace water from the surface. DOPA is also involved in the cross-linking reaction which in nature is catalyzed by the enzyme catechol oxidase .

The cross-linking can also be initiated by addition of an oxidant or by simply increasing the pH to above 8 where the reaction occurs spontaneously. DOPA forms extremely strong bonds to certain metals and metal oxides (iron, copper, aluminum, zinc, titanium). The strong bonds between metals and DOPA are likely to contribute to inhibition of corrosion.

The mussel adhesive is described in detail in the review article: Waite, J.H., Andersen, N.H., Jewhurst, and Sun, C. (2005) Mussel Adhesion: Finding the Tricks worth Mimicking. The Journal of Adhesion, 81, 297-317.