A Novel Astragalus Protein And Its Self-assembly

Astragalus is collectively for plants and herbal medicines. Astragalus is the representative of the beneficial and traditional Chinese medicines. The Astragalus is frequently-used medicine whoses smell is thin and dense,and it is non-toxic. Previous related researches mostly focused on the studies of the other active ingredients in Astragalus which less researched on the active ingredients of the protein. The protein have been separated and isolated from the Astragalus in this first study, and then researchded the self-assembly protein inculding the existing form, the basic characters, the entrapped drug and so on by the research methods of chemistry and biochemistry.The isolated target protein was determined the protein molecular size which is 35.5 kDa by SDS-PAGE. The protein is rich in glutamate(Glu,11.3%), serine(Ser, 11.12%), aspartic(Asp,8.42%), and leucine(Leu,8.17%) by amino acid composition analysis, but cysteine, tryptophan is not detected. The N-terminal sequence of the protein is AVXVEKPEVYKX?V, which is not high with other protein sequence through homology analysis, and many of which are derivd from microorganisms. So we believe the protein is a novel protein.To study the influence condition of the protein self-assembled nano-particles by dynamic light scattering(DLS) which measured the average size and Zeta potential in different pH (3.3-10.3), temperatures (60℃,80℃,100℃), incubation time(0-120 min). The results showed that the self-assembled nano-particles formed stable and uniform when the factor were pH8.3,80℃,1 h. The formation rate of the self-assembly nano particles was 89.6% by the Folin-phenol method.In this experiment AST was extracted from Astragalus, and the protein as carrier prepared for self-assembly nanoparticles.And the free Astragaloside after embedding the content was measured by HPLC, then the embedded rate was 35.3%. The average diameter of the AST protein nanoparticles was measured which compared to the non-AST nanoparticles was more increased, and the particle stability also improved. The protein nanoparticles and AST protein nanoparticles were observed by SEM, and the result showed the particles appeared spherical or oval, and the size distributed uniform, which covered with 0.22 μm cellulose acetate membrane pores, and also confirmed the self-assembly nanoparticles.The cell experimental results showed that the protein has been noxious to MDCK cell, and LD50 is 11.2 μg/mL; The protein nanoparticles have been non-toxic to MDCK cell and Hep-G2 cell at all concentrations, just at the higgest concentration(250μg/mL) it has a slight toxic effect on L-02 cell and Caco-2 cell.