Abstract
An unnatural amino acid, 4-chlorophenylalanine (ClPhe), was incorporated into silk fibroin of Bombyx mori silk fiber in place of a portion of the phenylalanine (Phe) residues using transgenic silkworms that can incorporate unnatural amino acids (4-substituted analogues of Phe) into protein biosynthesis in the posterior silk glands. Raw silk fiber containing ClPhe in silk fibroin was reeled from cocoons, and its characteristics, such as its tensile properties, were investigated. The thermal properties of the degummed fiber were also characterized. The results indicated that the partial replacement of Phe to ClPhe in silk fibroin did not affect the basic properties of Bombyx mori silk fiber.
