Spider silk ampullate spidroin

From the viewpoint of zootaxa, the silkworm and the spider belong to insect and arachnid of arthropod, respectively. Their silk proteins (fibroin for silkworm silk and spidroin for spider major ampullate silk) do not have any genetic heritage in common and their amino acids sequence compositions are different too. However, the silkworm and spider employ a similar spinning process to produce silk. Furthermore, the silkworm silk and the major ampullate silk have a number of similar structural characteristics, both at the level of the secondary protein structure and the condensed silk morphology. Therefore, for the sake of convenience, they are discussed together in some parts of this text. 

Chimeric (fusion) proteins that incorporate the R5 peptide have been synthesized to control and precipitate silica nanoparticles. Po Foo and coworkers have utilized a two-component chimeric protein consisting of the R5 polypeptide (from C. fusiformis) and the self-assembling domain based on the consensus repeat in the major ampullate spidroin protein 1 (MaSpl) of Nephila clavipes spider dragline silk [64]. MaSpl forms highly stable P-sheet secondary stmctures that can be spun into intricate fibers which, when fused with the sihca-templating R5-peptide, allow for the formation of film-like and fibrous silica structures (Figure 1.18). 

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