RESUMEN
Objective:Identification of some biochemical and physical properties for a new recombinant B7-2-PE40KDEL exotoxin fusion protein.Methods:12%SDS-PAGE separating and gel imaging analyzing,peptide mass fingerprinting,Western blot and MTT assasying were used respectively for identification of the protein.Results:Molecular weight of the recombinant B7-2-PE40KDEL was 72 628,5% of the difference to its theoretical value 69 561.The result of Western blot indicated that the purified recombinant B7-2-PE40KDEL could specifically bind with mAb anti-human B7-2 and the antibody against PEA,while the negative control did not.The recombinant B7-2-PE40KDEL digested with trypsin and then detected by MOLTI-TOF-MS.It was shown that the detected 15 peptides lied in the extracellular part of B7-2 and the truncated Pseudomonas extoxin PE40KDEL.Searching in the peptident data bank of Expasy website,we did not find any known proteins which was accordant with the above terms.The cytotoxic activity of the recombinant toxin with MTT method showed that the B7-2-PE40KDEL selectively killed Jurkat cell line which expressesed CD28 receptor well and had no killing effect on the Raji cell line unexpressing CD28 receptor.Conclusion:Recombinant B7-2-PE40KDEL exotoxin fusion protein we construct proves to be a new one with targeted killing bioactivity to B7:CD28 system.