Protein Adsorption And Elution Behaviors On Diethylaminoethyl-dextran Grafted Sepharose Gel

Two series of diethylaminoethyl dextran?DEAE-dextran?grafted agarose based ion exchangers?grafting-ligand resin FF-DexD modified with the DEAE-dextran;and mixed-ligand resin FF-D-DexD modified with both DEAE-dextran and DEAE?showed high adsorption capacity and fast uptake rate on bovine serum albumin adsorption.The improved protein capacity on dextran grafted resins is attributed to the three-dimensional DEAE-dextran grafting layer,and the rapid protein transfer is facilitated by the“chain delivery”effect of the DEAE-dextran chains and surface-ligands as the role of“transfer stations”.Herein,we focused on the impacts of the DEAE-dextran grafted ion exchangers,and the details of this work are summarized as follows.Firstly,considering the effect of the environmental factor to ion-exchange chromatographic behaviors,the difference in binding and elution behaviors of FF-DexD100 and FF-D50-DexD100 with four counterions was investigated and compared with three commercial resins?Q Sepharose FF?Q Sepharose XL and DEAE Sepharose FF?.The results show that the DEAE-resins showed the same orders for the counterion preference,in other words,the preference differences are only related to the chemical properties of the ligands,but not to the positions of the ligands?the surface-ligand or the grafting-ligand?.Besides,for the two DEAE-dextran grafted resins,the counterion of higher preference will promote protein elution,but decrease equilibrium adsorption capacity and uptake rate,so it finally reduce the dynamic adsorption capacity.Therefore,selecting favorable counterion in each operation process can be a useful strategy to optimize protein chromatography performance:herein,we can select HPO₄^2-in adsorption process,and SCN^-in elution process.Then,considering the effect of the sample factor to ion-exchange chromatographic behaviors.The adsorption and uptake behaviors of two proteins?BSA and?-globulin?with different molecular size and pI values on FF-DexD with different ion exchange capacity?IC?were investigated.The results show that the four FF-DexD resins offered higher adsorption capacities and faster mass transfer rates for the two proteins compared with the commercial DEAE Sepharose FF.However,because of the larger molecular size of the?-globulin,pore size of the resins with high DEAE-dextran grafting density too small to block the entry of?-globulin,which leads to the decrease of adsorption capacity.Meanwhile,due to the decrease in the amount of the bound protein,the contribution of surface diffusion to the whole mass transfer was weakened,and the mass transfer resistance increased because of the small pores,leading to the decrease in mass transfer rate.The results of this work will help the understanding of the chromatographic behaviors of functionalized-polymer grafted ion-exchangers,and benefit the practical application of these resins.