Polyphenolic proteins are proteins produced by some algae and marine invertebrates like the blue mussel, Mytilus edulis or the polychaete Phragmatopoma californica that are used as bioadhesives. These proteins contain a high level of L-DOPA

Levodopa

L-DOPA is a chemical that is made and used as part of the normal biology of some animals and plants. Some animals including humans make it via biosynthesis from the amino acid L-tyrosine. L-DOPA is the precursor to the neurotransmitters dopamine, norepinephrine , and epinephrine collectively...

 and cystine

Cystine

Cystine is a dimeric amino acid formed by the oxidation of two cysteine residues that covalently link to make a disulfide bond. This organosulfur compound has the formula 2. It is a white solid, and melts at 247-249 °C...

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The blue mussel protein is called mefp-5. The one for the Mediterranean mussel, Mytilus galloprovincialis, is called fp-5, fp being the abbreviation for foot protein.

In the zebra mussel (Dreissena polymorpha), two different protein precursors, Dpfp-1 and Dpfp-2, have been isolated and localized in the juncture between byssus

Byssus

Byssus means both a silky filament by which certain molluscs attach themselves to hard surfaces, and a rare fabric, also called sea silk and its fibre source.-Word:...

 threads and adhesive plaque.

Polyphenolic proteins can be polymerised in vitro using a mushroom tyrosinase

Tyrosinase

Tyrosinase also known as monophenol monooxygenase is an enzyme that catalyses the oxidation of phenols and is widespread in plants and animals...

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