A mixed-mode resin with tryptamine ligand for human serum albumin separation

Mixed-mode chromatography (MMC) is a new technology that uses specially-designed ligands to improve the adsorption selectivity with multimodal protein-ligand interactions for protein separation. A new MMC resin TA-B-6FF with tryptamine as the functional ligand was prepared and used for human serum albumin (HSA) separation. Adsorption equilibria of plasma-derived HSA (pHSA) were investigated and compared with a commercial tryptophan-based resin (MX-Trp-650m), and the influence of pH and salt addition was studied. The results showed that weak acidic conditions (pH 5.0-7.0) were favorable for HSA adsorption. The maximum adsorption capacity of TA-B-6FF was 141.33 mg/g at pH 5.0, which was two times higher than that of MX-Trp-650m. TA-B-6FF also showed better salt-tolerance than MX-Trp-650m. Moreover, TA-B-6FF was used to separate recombinant HSA (rHSA) from Pichia pastoris culture broth. The results indicated that rHSA could be directly captured by TA-B-6FF without dilution or pH adjustment. High purity (87.75%) of rHSA monomer could be obtained with a recovery of 98.53% through two-step elution process. Total content of rHSA monomer and degraded fragment was 99.75%, the removal of host cell proteins reached about 90%. The results demonstrate that new TA-B-6FF resin has a great potential for rHSA purification directly from the complex fermentation broth.