Mussel glue from Mytilus californianus Conrad: a comparative study.

Marine mussels secrete a byssus in order to attach to solid surfaces in the sea. The polyphenolic protein is the "glue" in the adhesive plaques of the byssus. In Mytilus californianus, the polyphenolic protein has an apparent molecular weight of 85,000 +/- 5,000 and is rich in the amino acids lysine, 3,4-dihydroxyphenylalanine, serine, threonine, and hydroxyproline. In composition it resembles the polyphenolic protein of M. edulis (Mr = 125,000), although the M. edulis protein contains significantly less isoleucine and more alanine. Tryptic digestion of M. californianus polyphenolic protein revealed two types of repeating decapeptides (1) (Ser/Thr)-Thr-(Tyr/Dopa)-Hyp-Hyp-Thr-Dopa-Lys-Hyp-Lys and (2) Ile-(Thr/Ser)-(Tyr/Dopa)-Hyp-Hyp-Thr-Dopa-Lys-Hyp-Lys. Residues 2 to 8 are identical with residues 4-10 in M. edulis decapeptides.