Antibody Capture from Corn Endosperm Extracts by Packed Bed and Expanded Bed Adsorption

• Published in: Biotechnology progress 2005-03, Vol.21 (2), p.473-485
• Main Authors: Menkhaus, Todd J., Glatz, Charles E.
• Format: Article
• Language: English
• Subjects: Adsorption; Antibodies - isolation & purification; Chromatography; Chronic infection; Endosperm; Glass beads; Mass transfer; Monoclonal antibodies; Plant Extracts - chemistry; protein purification; Q1; Q2; Resins; Substance P; Zea mays; Zea mays - chemistry
• ISSN: 8756-7938; 1520-6033
• DOI: 10.1021/bp049689s

Topical treatments of chronic infections with monoclonal antibodies will require large quantities of antibodies. Because plants have been proven capable of producing multisubunit antibodies and provide for large‐scale production, they are likely hosts to enable such applications. Recovery costs must also be low because of the relatively high dosages required. Hence, we have examined the purification of a human secretory antibody from corn endosperm extracts by processing alternatives of packed bed and expanded bed adsorption (EBA). Because of the limited availability of the transgenic corn host, the system was modeled by adding the antibody to extracts of nontransgenic corn endosperm. Complete clarification of a crude extract followed by packed bed adsorption provided antibody product in 75% yield with 2.3‐fold purification (with antibody accounting for 24% of total protein). The small size of the packed bed, cation‐exchange resin SP‐Sepharose FF and the absence of a dense core (present in EBA resins) allowed for more favorable breakthrough performance compared to EBA resins evaluated. Four adsorbents specifically designed for EBA operation, with different physical properties (size and density), chemical properties (ligand), and base matrices were tested: SP‐steel core resin (UpFront Chromatography), Streamline SP and Streamline DEAE (Amersham Biosciences), and CM Hyper‐Z (BioSepra/Ciphergen Biosystems). Of these, the small hyperdiffuse‐style resin from BioSepra had the most favorable adsorption characteristics. However, it could not be utilized with crude feeds due to severe interactions with corn endosperm solids that led to bed collapse. UpFront SP‐steel core resin, because of its relatively smaller size and hence lower internal mass transfer resistance, was superior to the Streamline resins and operated successfully with application of a crude corn extract filtered to remove all solids of >44 μm. However, the EBA performance with this adsorbent provided a yield of only 61% and purification factor of 2.1 (with antibody being 22% of total protein). Process simulation showed that capital costs were roughly equal between packed and expanded bed processes, but the EBA design required four times greater operating expenditures. The use of corn endosperm as the starting tissue proved advantageous as the amount of contaminating protein was reduced ∼80 times compared to corn germ and ∼600 times compared to canola. Finally, three different inlet designs (mesh, gl