The bioadhesive ofPhragmatopoma californica tubes: a silk-like cement containingL-DOPA

Summary

The marine polychaetePhragmatopoma californica (Fewkes) (Sabellariidae) lives within a tube that it constructs by cementing together material such as sand and shells. All of the carbon and nitrogen in the cement (determined by CHN combustion elemental analysis) can be accounted for as protein, although other organic constituents were not specifically looked for. Although the cement may be comprised of more than one protein, amino acid analysis reveals a similarity to the silk protein, sericin, which is the sticky outer covering on silk fibers. The short-chain amino acids comprise 60% of the total residues (glycine: 24%, alanine: 7%, and serine: 29%). Lysine is the next most abundant residue (12%), with basic amino acids totalling 19% of the total residues. Amino acids with hydroxyl side-chains account for 35% of the total. The amino acid DOPA (3,4-dihydroxyphenylalanine), which is present as 2.6% of the total residues, probably acts to stabilize the material through quinone tanning and/or by forming adbesive-type complexes with substrata. The cement thus displays structural and functional similarities with the cement ofMytilus spp. (Waite 1987) and with silk.