Byssus threads of the green mussel attach to a wet, solid surface due to glycosylated hydroxytryptophan in one of its adhesive proteins.

Some mussels adhere to rocks and other ocean substrates using a protein that contains an amino acid called Dopa (3,4-dihydroxyphenyl-L-alanine). However, the invasive green mussel, Perna viridis, has a more complcated adhesive chemistry based on a protein with an elaborate modification of the amino acid tryptophan.

The stickiness of the green mussel's foot, especially how it works in wet environments could be mimicked to form new adhesives, including use for teeth, bones, and for repairing ships at sea that have developed cracks.

(adapted from an article at


"The 3,4-dihydroxyphenyl-L-alanine (Dopa)-containing proteins of mussel byssus play a critical role in wet adhesion and have inspired versatile new synthetic strategies for adhesives and coatings. Apparently, however, not all mussel adhesive proteins are beholden to Dopa chemistry. The cDNA-deduced sequence of Pvfp-1, a highly aromatic and redox active byssal coating protein in the green mussel Perna viridis, suggests that Dopa may be replaced by a post-translational modification of tryptophan. The N-terminal tryptophan-rich domain of Pvfp-1 contains 42 decapeptide repeats with the consensus sequences ATPKPW1TAW2K and APPPAW1TAW2K. A small collagen domain (18 Gly-X-Y repeats) is also present. Tandem mass spectrometry of isolated tryptic decapeptides has detected both C2-hexosylated tryptophan(W1) and C2-hexosylated hydroxytryptophan(W2), the latter of which is redox active.The UV absorbance spectrum of W2 is consistent with 7-hydroxytryptophan, which represents an intriguing new theme for bioinspired opportunistic wet adhesion." (Zhao et al. 2009:23344)

Journal article
Glycosylated Hydroxytryptophan in a Mussel Adhesive Protein from Perna viridisJournal of Biological ChemistryAugust 7, 2009
H. Zhao, J. Sagert, D. S. Hwang, J. H. Waite