Peptide repeats in a mussel glue protein: theme and variations.
The adhesive protein from Mytilus edulis contains 75-80 closely related, repeated peptide sequences in its primary structure. These peptides can be resolved following digestion with trypsin by reversed-phase high-pressure liquid chromatography. The most frequently repeated sequence is the decapeptide Ala-Lys-Pro-Ser-Tyr-Hyp-Hyp-Thr-Dopa-Lys (peptide E). Variations of this occur in peptides B with Hyp-3 and Dopa-5, C with Dopa-5, and D with Hyp-3, respectively. Lesser amounts of hexapeptides (A and B') that are lacking residues 4-7 also occur. Peptide A has the sequence Ala-Lys-Pro-Thr-Dopa-Lys, whereas B' contains Tyr instead of Dopa. 4-Hydroxyproline occurs at positions 3 and 7 and occasionally at position 6 of the decapeptide; 3-hydroxyproline occurs only at position 6. Adhesiveness of the protein may be related to the repetition of Dopa residues, the catecholic moiety of which has strong hydrogen-bonding and metal-liganding capabilities.
D000595:Amino Acid Sequence; D000818:Animals; D049872:Bivalvia / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D005088:Exocrine Glands / Q000032:analysis; D010446:Peptide Fragments / Q000032:analysis; D011506:Proteins / Q000302:isolation & purification*
D010446:Peptide Fragments; D011506:Proteins; C037403:adhesive protein, mussel