Base On Preparation Of The Environment, The Molecular Conformation And Biological Properties Of The Sericin Protein

Silk is a nature protein that is mainly made of sericin and fibroin protein, has been used long before. Silk sericin is a valuable protein resource discarded during producing fabrics. Studieds have proved that sericin is a good globular protein, has good biocompatibility, biodegradability and gel-sol transformation can be used as a specific range of biological materials. But sericin has complex structures, surface amino acid residues, and environmental mutability. In different extracting methods and conditions, its character may be different. According to the structure decided performance, performance and characteristics in change may affect its biological properties,so that it appears to be impeding the process of development and restricts the development of biological materials. In this paper, base on two common sericin preparation environment, such as sericin protein was extracted from cocoon shell and cocoon outer floss respectively, the sericin protein peptide from cocoon shell was prepared by neutral proteinase. It was characterized by the molecular weight determination,the infrared spectroscopy(IR), amino acid composition and content measurement,solubility test, respectively. Exploring the evolution of the molecular properties and conformation which was extracted in common preparation methods and physical environment. And observe the corresponding relationship between the molecular conformation and biological performance (antibacterial and cytotoxicity). The molecular weight of the Jk1, Jk2, Jk3 was about 66.2 kDa-130kDa, and that of the Jy4 was about 43kDa-200kDa, the Jkmj5 was under 3kDa.The solubility,IR and amino acid composition analysis showed that: 1,The sericin protein extracted on the same extraction conditions from the cocoon shell is with relatively stable properties ; 2,Jk1, Jk2, Jk3, Jy4 wereα-helix structure type mostly, and the random coil structure increased in Jy4; 3,Jkmj5 was the structure of corners and random coil mainly. Each sericin sample have antibacterial effects to Staphylococcus aureus and E.coli, but sericin sample of Staphylococcus aureus antibacterial more significant. Cultured mouse fibroblasts L-929 in culture media which have three concentration of the three sericin sample (Jk1, Jy4, Jkmj5). Using the MTT method and observing with inverted microscope, the results showed that the various concentrations of the three sericin sample have no inhibition effect on cell growth, Jy4 and Jkmj5 can promote the growth and to with the increase of concentration, the more obvious role in promoting. Various concentrations of three sericin protein have no obvious effect on cell morphology. Three groups of the sericin have higher relative growth rate, including Jk1 part RGR grading standard 1, other RGR grading 0 level , Jy4 and Jkmj5 belong to the RGR grading standards 0 level, almost no toxicity. Jy4 and Jkmj5 show better biocompatibility than Jk1.