The Functional Motif of SARS-CoV S Protein Involved in the Interaction with ACE2 / 中国病毒学

SARS-CoV is a newly discovery pathogen causing severe acute respiratory problems.It has been established that the S protein in this pathogen plays an important rule in the adsorption and penetration of SARS-CoV into the host cell by interaction with the ACE2 receptor.To determinant which functional motif of the S protein was involved in the interaction with ACE2,seven truncated S proteins deleted from the N or C terminal were obtained by an E.coli expression system and purified by column chromatography to homogeneity.Each truncated S protein was fixed on to the well of an ELISA plate and an interaction was initiated with the ACE2 protein.The adsorption were quantified by ELISA,and the results indicated that amino acids from 388 to 496 of the S protein was responsible for the interaction with the ACE2 receptor,and the interaction could be completely disrupted by an antibody specific to these amino acids.Deletions adjacent to this domain did not appear to have a significant impact on the interaction with ACE2,suggesting that the S protein of SARS-CoV could be developed as a vaccine to prevent the spread of SARS-CoV.

The purification of HBV full-length PreS protein in Pichia pastoris / 生物工程学报

The Pichia pastoris strain GS115-PreS could produce a high expression level of full-length PreS protein that secreted to the supernatant after methanol induction in the fermentation. The Western blot analysis showed a single band with expected molecular mass of 48kD and that the major component of the particles was the full-length PreS protein (PreS1 + PreS2 + S) and small envelope protein (S) of 48 and 28 kD, respectively. Electron microscopy image showed PreS particles with 30 nm in diameter. The supernatants of the fermentation were desalted and concentrated. Purified PreS protein was obtained by DEAE-SFF anion exchange column chromatography and the PreS particles were obtained by ultracentrifugation and sucrose density gradient. The ELISA assay results proved that both full-length PreS protein and particles showed high immunogenicity and specificity. P/N ratio further demonstrated that the immunogenicity of the particles is higher than the full-length PreS protein.