Optimal operation conditions for protein separation in hydrophobic interaction chromatography

Different Stationary Phase Selectivities and Morphologies for Intact Protein Separations

The central dogma of biology proposed that one gene encodes for one protein. We now know that this does not reflect reality. The human body has approximately 20,000 protein-encoding genes; each of these genes can encode more than one protein. Proteins expressed from a single gene can vary in terms of their post-translational modifications, which often regulate their function within the body. Understanding the proteins within our bodies is a key step in understanding the cause, and perhaps the solution, to disease. This is one of the application areas of proteomics, which is defined as the study of all proteins expressed within an organism at a given point in time. The human proteome is incredibly complex. The complexity of biological samples requires a combination of technologies to achieve high resolution and high sensitivity analysis. Despite the significant advances in mass spectrometry, separation techniques are still essential in this field. Liquid chromatography is an indispensable tool by which low-abundant proteins in complex samples can be enriched and separated. However, advances in chromatography are not as readily adapted in proteomics compared to advances in mass spectrometry. Biologists in this field still favour reversed-phase chromatography with fully porous particles. The purpose of this review is to highlight alternative selectivities and stationary phase morphologies that show potential for application in top-down proteomics; the study of intact proteins.

Composite cryogels for lysozyme purification

Beads-embedded novel composite cryogel was synthesized to purify lysozyme (Lyz) from chicken egg white. The poly(hydroxyethyl methacrylate-N-methacryloyl-L-phenylalanine) (PHEMAPA) beads of smaller than 5 µm size were synthesized by suspension polymerization and then embedded into a poly(hydroxyethyl methacrylate) (PHEMA)-based cryogel column. The PHEMAPA bead-embedded cryogel (BEC) column was characterized by swelling tests, scanning electron microscopy (SEM), surface area measurements by the Brunauer-Emmett-Teller (BET) method, elemental analysis, and flow dynamics. The specific surface area of the PHEMAPA BEC was found as 41.2 m(2) /g using BET measurements. Lyz-binding experiments were performed using aqueous solutions in different conditions such as initial Lyz concentration, pH, flow rate, temperature, and NaCl concentration of an aqueous medium. The PHEMAPA BEC column could be used after 10 adsorption-desorption studies without any significant loss in adsorption capacity of Lyz. The PHEMAPA BEC column was used to purify Lyz from chicken egg white, and gel electrophoresis was used to estimate the purity of Lyz. The chromatographic application of the PHEMAPA BEC column was also performed using fast protein liquid chromatography.

Methods of calculating protein hydrophobicity and their application in developing correlations to predict hydrophobic interaction chromatography retention

Hydrophobic interaction chromatography (HIC) is a key technique for protein separation and purification. Different methodologies to estimate the hydrophobicity of a protein are reviewed, which have been related to the chromatographic behavior of proteins in HIC. These methodologies consider either knowledge of the three-dimensional structure or the amino acid composition of proteins. Despite some restrictions; they have proven to be useful in predicting protein retention time in HIC.

A highly efficient integrated chromatographic procedure for the purification of recombinant hepatitis B surface antigen from Hansenula polymorpha

The high expression level of recombinant hepatitis B surface antigen obtained from Hansenula polymorpha yeast cell (Hans-HBsAg) made it possible to produce HBsAg vaccine in a large scale and by cost-effective process. However, the present available purification process was somewhat tedious, time-consuming and difficult to scale up. To improve the purification efficiency and simplify the purification process, an integrated chromatographic process was developed and optimized. The downstream process included ion-exchange chromatography (IEC), hydrophobic interaction chromatography (HIC) and gel filtration chromatography (GFC). A series of chromatographic adsorbents were evaluated for their performances on the purification of Hans-HBsAg, and then the suitable adsorbents for IEC and HIC were screened out, respectively. After clarification by centrifugation, the supernatant of cell disruption (SCD) was purified by standard chromatographic steps, IEC on DEAE Sepharose FF, HIC on Butyl-S-QZT and GFC on Sepharose 4FF. Furthermore, HBsAg recovery, purification factor (PF) and purity during the downstream process were evaluated with enzyme-linked immunosorption assay (ELISA), sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and high-performance size-exclusion chromatography (HPSEC). The results demonstrated that in the scale of 550ml SCD, the total HBsAg recovery and PF of the whole procedure were about 21.0+/-0.9% and 80.7+/-8.4 (n=3) respectively, with the purity of above 99%. This new downstream process was efficient, reproducible and relatively easy to be scaled up.

Comparison of standard and new generation hydrophobic interaction chromatography resins in the monoclonal antibody purification process

Recent efforts to improve hydrophobic interaction chromatography (HIC) for use in monoclonal antibody (mAb) purification have focused on two approaches: optimization of resin pore size to facilitate mAb mass transport, and use of novel hydrophobic charge induction (HCIC) mixed mode ligands that allow capture of mAbs under low salt conditions. We evaluated standard HIC and new generation HIC and HIC-related chromatography resins for mAb purification process efficiency and product quality both as isolated chromatography steps and in purification process trains. We find that HIC resins with optimized pore size have significantly improved binding capacity which can increase HIC purification unit operation efficiency. The HCIC Mercapto-Ethyl-Pyridine (MEP) resin, which shows a different salt impact trend and impurity resolution pattern from standard HIC resin, can not only capture mAb from crude CHO fermentation supernatant but also substantially enhance mAb purification process flow efficiency when serving as a polishing role.