Abstract:

BACKGROUND: Sericin has been widely used as a biomaterial. The properties and function of sericin may be changed with different extraction methods and conditions, thus affecting the biological properties.
OBJECTIVE: To observe the changes of sericin molecular conformation using different materials and under different preparation conditions.
METHODS: Sericin protein was extracted under the same extraction conditions from cocoon shell (Jk1, Jk2, Jk3) and cocoon outer floss (Jy4), respectively. Sericin protein peptide from cocoon shell (Jkmj5) was prepared by neutral proteinase. It was characterized by the molecular weight determination, infrared spectroscopy, amino acid composition and content measurement, solubility test, respectively
RESULITS AND CONCLUSION: When sericin extracted from cocoon shell and cocoon outer floss, there were significant differences in molecular weight determination, amino acid composition and content measurement. The molecular weight determination of Jk1, Jk2, Jk3 was about 66 200-130 000, respectively, while that of the Jy4 was about 43 000-130 000. The aspartic acid, serine, threonine and glycine contents decreased, while glutamic acid and lysine increased significantly in sericin extracted from cocoon outer floss compared with that extracted from cocoon shell. By the infrared spectroscopy, Jk1, Jk2, Jk3, Jy4 were mostly α-helix structure type, and the random coil structure increased in Jy4. The dissolving property of Jy4 was almost twice that of Jk1, Jk2, Jk3. Jkmj5 was the structure of corners and random coil mainly. The sericin protein extracted on the same extraction materials and conditions has similar composition and stable properties.