Mussel adhesives amino acid sequence

Isolation and Characterization of cDNA Clones Encoding the Poly-phenolic Protein. Characterization of the primary amino acid sequence of the mussel adhesive protein has been hindered by the large size of the protein and the repetitiveness of the amino acids. In such cases, the practical (and perhaps only) approach for determining the complete amino acid sequence is to clone DNA sequences encoding the protein and to deduce the amino acid sequence from the genetic code carried by that DNA. To accomplish this, we obtained mRNA from mussels and synthesized cDNA in vitro. 

The chemical reactions discussed above are not by themselves sufficient to develop a mechanistic scheme for underwater glue formation unless they are reviewed in the context of the three-dimensional structure of the mussel adhesive protein. The structure of this protein however is not available. We therefore decided to derive its three-dimensional structure from the consensus decapeptide sequence in an incremental fashion using computer modeling and chemical intuition. It is well-known that the primary amino acid sequence determines the structure of a protein. However, predicting three-dimensional structures from an amino acid sequence is a risky venture unless there are experimental guide posts that support or reject the predicted structures. 

Structural proteins such as collagen, elastin, and spider silk contain repeating sequences of amino acids. In 1983, Waite discovered that the protein secreted by the phenol gland of the blue sea mussel Mytilus edulis consists of closely related decapeptide and hexapeptide sequences with a combined molecular weight of approximately 130 kilodaltons (kDa).i He further elucidated that this protein is transformed into glue through enzymatic oxidation to form the adhesive plaques that anchor the mussel... 

To develop a mechanistic scheme for glue formation at the molecular level, it is important to know which amino acids in the mussel adhesive protein and collagen are oxidized and to follow the fate of these amino acids in subsequent secondary reactions such as crosslinking, complexa-tion, degradation, etc. Once the sequence of chemical events is established, it can be applied to the three-dimensional structures of mussel glue protein and collagen to develop a rational model for glue formation. 

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