大肠杆菌表达的戊型肝炎病毒ORF2片段的聚合现象研究

在大肠杆菌中表达了戊型肝炎病毒（HEV）ORF2的a.a.394～a.a.604片段，得到的重组蛋白NE2在SDSPAGE中主要以可被尿素解聚的二聚体形式存在，二聚体对病人血清的反应性明显强于单体；质谱分析表明NE2可形成从二聚体到至少六聚体的多种聚体；动态光散射测定表明平均分子半径约4nm，相当于四聚体，但分散度较大，提示为多种大小不一的聚合体的混合物。这些证据表明NE2蛋白可形成以同源二聚体为基本单位的多种聚合体形式，其中以二聚体间的结合最为紧密，并且以二聚体为基础可进一步装配出多种更高级结构，从而具有作为HEV疫苗及诊断试剂抗原的良好前景。 

The Study of Aggregate of the ORF2 Peptide of Hepatitis E Virus Expressed in Escherichia coli

A fragment of hepatitis E virus open reading frame-2(ORF2), located from amino acid residues 394 to 604, was expressed in E.coli. The recombinant protein NE2 was found to form homodimer mostly in SDS-PAGE, which can be dissociated to monomers when treated with urea, and it was recognized more strongly in its dimeric form than the monomer by HEV reactive human serum in Western blotting. Besides, many aggregated form of NE2 from dimer to at least hexamer can be seen in MALDI-TOF-MS. And when the hydrated dynamic semidiameter of NE2 moleculars in PBS was measured as about 4nm by Dynamic Light Scattering (DLS), being equal to tetramer, but with high polydispersity, which suggested that the NE2 moleculars were existed in PBS in many different sizes. These results suggested that the recombinant NE2 can aggregate into several oligomer forms, the association in the dimer is most strong,and dimers can assemble further to form some super-structure.