Weijie Song

Directing membrane chromatography to manufacture α1-antitrypsin from human plasma fraction IV.

The surging demand for plasma proteins, mainly driven by the growing market and the development of new therapeutic indications, is promoting manufacturers to improve the throughput of plasma proteins. Due to the inherent convective mass transfer, membrane chromatography has been proved to be an efficient approach for extracting a small amount of target proteins from large-volume feed. In this study, α1-antitrypsin (AAT) was extracted from human plasma fraction IV by a two-step membrane chromatography. An anion-exchange membrane chromatography (AEMC) was used to capture the plasma proteins in bind/elute mode, and the obtained effluent was further polished by a hydrophobic interaction membrane chromatography (HIMC) in flow-through mode. Under optimal conditions, the recovery and purity of AAT achieved 87.0% and 0.58 AAT/protein (g/g) by AEMC, respectively. After the precise polishing by HIMC, the purity of AAT was 1.22 AAT/protein (g/g). The comparison results showed that membrane chromatography outperformed column chromatography in both steps because of its high throughput. This two-step membrane chromatography could obtain an AAT recovery of 83.3% and an activity recovery of 91.4%. The outcome of this work not only offers an alternative process for protein purification from plasma, but also provides guidelines for manufacturing product from a large-volume feed with multi-components by membrane chromatography.

Recycling cellulase from enzymatic hydrolyzate of acid treated wheat straw by electroultrafiltration

This work explores the feasibility of recycling cellulase by electroultrafiltration (EUF), an ultrafiltration process enhanced by an electric field, to reduce the cost of enzymatic transformation of cellulose. The effect of electric field under different operating conditions (buffer concentration, acid treated wheat straw concentration, current and temperature) on flux during EUF was examined. The results showed that EUF was effective to reduce concentration polarization (CP) and enhance filtration flux in recycling cellulase. The flux improvement by the electric field could be strengthened at low buffer concentration (5 mM) and relatively low temperature (room temperature) and high current (150 mA). The flux for 2% (substrate concentration, w/v) lignocellulosic hydrolyzate increased by a factor of 4.4 at 836 V/m and room temperature, compared to that without electric field. This work shows that under appropriate operating conditions EUF can efficiently recycle cellulase from lignocellulosic hydrolyzate and thus substantially reduce hydrolysis cost.