Model polypeptide of mussel adhesive protein. I. Synthesis and adhesive studies of sequential polypeptides (X-Tyr-Lys)(n) and (Y-Lys)(n)

The sequential polytripeptides and polydipeptides, (X-Tyr-Lys)(n), (X=Gly, Ala, Pro, Ser, Leu, Ile, Phe), (Y-Lys)(n), (Y=Gly, Tyr), and (Gly-Tyr)(n), which imitate a mussel adhesive protein, have been synthesized. The molecul ar weights of the polypeptides were estimated to be 7,200 similar to 13,400 (19 similar to 42 repeating units), and the polypeptides were found to hav e satisfactory amino acid sequences. The polypeptides were crosslinked by t yrosinase, and the optimal pH in the crosslinking reaction was 7.4 in the c ase of the polytripeptide, (Gly-Tyr-Lys)(n). The optimal tyrosinase amount for the adhesive strength of(Gly-Tyr-Lys)(n) was 0.34 unit/mg (polypeptide) at pH 7.4. The shear adhesive strength of the polytripeptide increased wit h an increase in the polytripeptide concentration, and was not influenced b y the third amino acid, X. The shear adhesive strengths of polytripeptides (X-Tyr-Lys)(n) were equal to one of the synthetic polydecapeptides, (Ala-Ly s-Pro-Ser-Tyr-Pro-Pro-Thr-Tyr-Lys)(n) and (Gly-Pro-Lys-Thr-Tyr Pro-Pro-Thr- Tyr-Lys)(n) which were the model polydecapeptides for blue mussel and Calif ornian mussel, respectively. (C) 2000 John Wiley & Sons, Inc.