Mpegylation Of Thymopentin And Characterization

PEG modification technology was used to improve the nature of proteins and peptides, because that pegylation can reduce the in vivo immunogenicity and antigenicity, and successfully improve the in vivo bioavailability of the proteins and peptides. The TP5have a regulating effect on immune system, and in the treatment of immune disorders have an excellent prospect. In order to solve the problems of TP5in clinical applications, such as poor stability,.PEG modification technology was used in this paper.To improve the half-life of thymopentin by PEGylation, thymopentin was modified by two kinds of mPEG derivatives (mPEG-ButyrALD and mPEG-SPA) with different active moieties, and the concentration of TP5and the composition of mPEG-modified products were determined by the method of RP-HPLC. The optimization of reaction conditions was set goal-the highest proportion of mono-pegylated TP5, which were as follows:pH5.0, mPEG-ButyrALD/TP5(molar ratio)=2:1, and the reaction time=55min; pH8.5, mPEG-SPA/TP5(molar ratio)=2.5:1, and the reaction time=6min.The pegylated product was separated by cation exchange chromatography(SP-Sepharose Fast Flow). After desalting by ultrafiltration, freeze-drying the final product was obtained.The molecular weight, stabilities were tested, and the immunosuppressed mice model was created by X-Ray. The three injections as TP5, mPEG-ButyrALD-TP5and mPEG-SPA-TP5were gave to the immunosuppressed mice model separately, and compared their carbon clearance test. MALDI-TOF-MS proved these products to be single-PEGylated,and their molecular weight were5600. Compared to natural TP5, the PEGylated peptides showed higher stabilities in the trypsin. In the immunosuppressed mice, mPEG-ButyrALD-TP5was no significant effect, mPEG-SPA-TP5and TP5could increase the phagocytic coefficient of phagocytic cells, improved immune function, mPEG-SPA-TP5was significantly higher than that of the unmodified TP5to promote immunization efficacy and duration of action.