Inductively coupled plasma mass spectroscopy (ICP-MS) and atomic adsorption spectroscopy (AAS) were applied to determine the Fe and Mn contents in both silk glands and cocoon silks of Bombyx mori silkworms. In the meantime, Raman spectroscopy was used to monitor the effect of Fe(III) and Mn(II) on the conformation changes of silk protein in the concentrated regenerated silk fibroin solutions. The results showed that the Fe content in cocoon silk was higher than that in the silk gland, but the Mn content was on the other way round. In addition, the Fe content was gradually increased from the posterior part to the ante-rior part of the silk gland. However, the Mn content did not exhibit the same tendency as Fe did but showed the lowest value in the middle part of the silk gland. Finally the Raman spectra indicated that Fe(III) was able to induce the conformation transition of silk fibroin from random coil and/or helix conformation to β-sheet but Mn(II) seemed no such an effect.

Key words: metal element, concentrated regenerated silk fibroin solution, Raman spectroscopy, conformation transition, spinning mechanism, tyrosine