To obtain active hFKBP52 protein for screening novel neu rotrophic drugs. Semi-nested and overlap PCR and affinity chromatography were u sed. hFKBP52 gene was cloned successfully from human fetal brain cDNA library, a nd then highly expressed (about 30%) as fusion protein in pET28a(+) vector syste m. The recombinant protein was purified as one band on SDS-PAGE. The purified h FKBP52 showed peptidyl-prolyl cis-trans isomerase (PPIase) activity, simil ar to the wild type.

The primary structure of rhFK506-Binding Protein (FKBP) 12 was studied with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) by measuring its molecular weight and tryptic peptide mass fingerprinting.The calculated molecular weight of rhFKBP12 was 11819.5 and the measured value was 11818.0. The relative error was only 0.01%. The measured peptide mass fingrprinting of rhFKBP12was identical with that deduced from its amino acid sequence. It proved that the primary structure of rhFKBP12 was correct and there was no amino acid deletion, mutation and modification in its expression, refolding andpurification.

Objective: Immunotoxin rRTA:DS27, which was prepared by conjugating DS27 with recombinanl ricin a chain, was compared with ricin:DS27 as immunotoxins. Methods: System analysis were performed regard to their cell-specific cytotoxicity, inhibition on the proliferation of hemoapeutic potential cells, immunogold-labelled intracellular routing and effect of NH_(4)Cl on the cytotoxicity. Results: Results showed that rRTA: DS27 got a more specific cytotoxicity and a weaker inhibition on the proliferation of hemoapeutic potential cells than ricin:DS27, NH_(4)Cl could obsolutelyy enhence the cytotoxicity of rRTA:DS27. Conclusion: rRTA:DS27 had more advantages than ricin: DS27 as immunotoxins.

The key to killing target cells by immunotoxin depends on the specific recognition of antibody to target cell and the cytotoxic effect of toxin. The comparative study of the killing effects of two anti-T immunotoxins, CD5:Ricin and CD5:rRA, on target cells was performed. The elimination rate of immunotoxins was analysed by flow cytometry and MLR. The effect of immunotoxins on the proliferation of hematopoiesis was evaluted by CFU-GM. The results showed that (1) CD5(+) T cells were eliminated and CD25(+) CD3(+) activated T cells were concentration-dependently inhibited by the two immunotoxins in the range of 10(-9) - 10(-11) mol/L; (2) both immunotoxins significantly inhibited the mixed lymphocyte reaction, and the inhibiting effect of CD5:rRA to T cell proliferation was markedly lower than that of CD5:Ricin in the range of 10(-10) - 10(-11) mol/L; (3) the combination of CD5:rRA with 10 mmol/L NH(4)Cl increased the T cell elimination rate; and (4) the two immunotoxins and the combination of NH(4)Cl and CD5:rRA did not suppressed proliferation of granulocyte-macrophage progenitors in the range of concentrations with killing effect. It was concluded that T cell and activated T cell could be eliminated effectively by immunotoxins, the proliferation of granulocyte-macrophage progenitor was not inhibited significantly.