Proline-rich silk proteins produced by the larvae of the mulberry pyralid Glyphodes pyloalis
2004
Yamada, H. (National Inst. of Agrobiological Sciences, Tsukuba, Ibaraki (Japan)) | Igarashi, Y. | Takasu, Y. | Tsubouchi, K. | Kato, Y.
We carried out biochemical investigation on proteinaceous components of the silk produced by the larvae of the mulberry pyralid Glyphodes pyloalis. When this silk was treated with hot aqueous 8M urea, 7.5 % of the material in weight was extracted, and named as the pyralid sericin. About 10 % of the residue in weight was dissolved in aqueous saturated lithium thiocyanate, and the protein extracted was named as the pyralid fibroin. Amino acid composition analysis of the sericin showed unusually high content of proline (13.3 mole %) in contrast with that of Bombyx mori (0.7 mole %) sericin. Size exclusion chromatography revealed that the sericin is composed of two polypeptides of 300 and 40 kDa. On the other hand, the pyralid fibroin was also found to contain a high content of proline up to 22.8 mole %, whereas the proline content in B. mori fibroin is 0.3%. It was a single polypeptide of molecular mass of 350 kDa or more. Key words: mulberry pyralid, Glyphodes pyloalis, sericin, fibroin, amino acid composition, SDS-PAGE, molecular mass
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