Separation of empty and full AAV8 capsids was achieved during their elution from a weak anion exchanger with an ascending pH gradient at low conductivity. Experimental data suggest elution was mediated by loss of positive charge from the exchanger. The method produced a full capsid peak with fewer empty capsids than elution of a strong anion exchanger with a salt gradient. Elution of the weak exchanger by sodium chloride gradients or by pH gradients in the presence of sodium chloride gave inferior separation performance. Pre-elution of empty capsids with a pH step allowed full capsids to be eluted by salt without compromising separation. Loading at intermediate pH prevented empty capsid binding and enabled step elution of full capsids in a physiological buffer environment.
Tag: <span>separation</span>
The diversity of the antibody-antigen interaction and our ability to manipulate this interaction has created an enormous potential for the discovery and development of IgG therapeutics and diagnostics. Along with the expanding clinical pipeline of antibody products, increasing efforts have been devoted to improving antibody production and purification procedures. In order to meet drug discovery needs with limited resources, the so called “flexible generic purification scheme” approach has been adopted to develop a robust manufacturing process that allows the application of similar operational conditions to different monoclonal antibody molecules…
Short Monolithic Columns — An Enabling Technology for the Purification of Proteins, DNA, and Viruses
The last 30 years have seen rapid and dramatic developments in recombinant DNA technology and the related biological sciences. In 1972, Paul Berg’s group used restriction enzymes to cut DNA in half and then used ligases to stick the pieces of the DNA back together. By doing this, they produced the first recombinant DNA. Within a year, the first genetically engineered bacterium existed. A little more than ten years later, recombinant human insulin was approved for diabetic patients and became the first recombinant healthcare product. Before the end of the 1980s, the first gene therapy trial had occurred. Today, a large number of recombinant proteins are used as marketed drugs and even more are in clinical trials targeting a wide range of diseases…
The Baculovirus Expression Vector System (BEVS) is widely used for the production of a broad variety of heterologous proteins that are often secreted into the culture medium as soluble, biologically active, properly glycosylated, and correctly folded. Downstream purification of a secreted protein is considerably easier due to the absence of many contaminating cellular proteins and nucleic acids in the culture supernatant. The BEVS system has also successfully been used for the production of virus-like particles (VLPs) for a broad variety of proteins derived from many different viruses…
A growing number of separations’ scientists and process developers are looking beyond protein A sorbents for capture and initial purification of monoclonal antibodies. A variety of strategic and operational goals have prompted examination of alternative immunoglobulin-selective sorbents. Most broadly, many workers wish to eliminate design considerations associated with leached protein A. Also cited is a preference for sorbents that can withstand stringent cleanup using 1 M sodium hydroxide. In some applications, it is desirable to avoid the low-pH elution conditions typically employed with protein A sorbents — conditions that can foster aggregate formation. In still other cases, the target antibody may bind poorly to protein A. Finally, there may be interest in evaluation of immunoglobulin-selective sorbents less costly than protein A sorbents…
One of the biggest challenges in the production of recombinant therapeutic proteins, monoclonal antibodies, and vaccines is the clarification and separation of the product (typically a protein) from the cell culture or fermentation broth. The desired product is present in low concentrations and must be efficiently separated from the other components present in the bioreactor fluid. An overall objective in developing a clarification process is to achieve the highest level of product recovery (yield) and contaminant removal with the fewest number of unit processes. Understanding how each operational step affects the performance of the next step downstream is the challenge at hand. Centrifugation, in combination with depth filtration, is gaining acceptance as the preferred method for the removal of cells, cell debris, colloids, insoluble precipitants, aggregates, and other materials found in mammalian cell culture and bacterial fermentation fluids…
Cation exchange chromatography (CEX) is a versatile method for separation of proteins based on exploiting differences in positive electrostatic charges. In CEX, proteins are bound to the negatively charged stationary phase (cation exchangers) and then eluted using a salt gradient. Typically, the liquid-phase pH in CEX is lower than the isoelectric points (pI) of the proteins. CEX has been used to monitor various post-translational modifications such as glycosylation, deamidation, phosphorylation, truncation, oxidation, C-terminal and N-terminal clipping, and N-terminal cyclization. Some of these variants may exhibit different bioactivity. Therefore, it is important to characterize protein variants and monitor the stability of these variants throughout the process of drug discovery, development, and manufacture. Characterization of complex proteins such as antibodies, has traditionally been performed using slab gel-based techniques such as isoelectric focusing (IEF). This technique is qualitative and time consuming. It also generates large quantities of chemical waste from the staining process…