Antibody Purification Using Anionic Polymer Precipitation
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Solution Overview
Problem
Current antibody purification methods, particularly those using precipitation techniques with anionic or cationic polymers, face challenges in effectively removing host cell-derived proteins (HCP) and DNA, especially for antibodies with low isoelectric points (pI), leading to low yield and impurity removal rates, and require complex and costly column chromatography processes.
Innovation Solution
A method involving the use of anionic polymers such as polyvinylsulfonic acid (PVS), polyacrylic acid (PAA), or polystyrenesulfonic acid (PSS) to adjust the pH of antibody compositions to values below the antibody's pI, allowing for the selective precipitation and removal of HCP and DNA without precipitating the antibody itself, thereby simplifying the purification process and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional column chromatography methods (Protein A/G affinity chromatography) are used for antibody purification, then high purity antibodies can be obtained, but the purification cost increases significantly and processing capacity is limited
Solution Approach 1:
The patent changes the pH parameter of the antibody solution to below the isoelectric point (pI) of the antibody. This parameter change causes the antibody to become positively charged, enabling selective precipitation with anionic polymers while leaving negatively charged impurities (HCP and DNA) in solution, thus achieving purification without complex column chromatography
Solution Approach 2:
The patent extracts and removes negatively charged impurities (HCP and DNA) from the antibody solution by adjusting pH and using anionic polymer precipitation. The impurities are separated from the positively charged antibody through differential solubility, allowing the antibody to remain in solution while impurities precipitate and can be removed
2Manufacturing precision
If pH is adjusted below the antibody's pI to enable anionic polymer precipitation, then impurity removal efficiency improves, but antibody yield may decrease due to potential antibody precipitation
Solution Approach 1:
The patent optimizes the pH parameter to be below but close to the antibody's pI, and controls the ionic strength and temperature parameters to prevent antibody precipitation while enabling impurity precipitation. This parameter optimization allows selective precipitation of impurities without significant antibody loss
Solution Approach 2:
The patent uses anionic polymers as intermediary substances that selectively interact with negatively charged impurities (HCP and DNA) at pH below antibody pI. The anionic polymer acts as a mediator that binds to impurities and causes their precipitation, while the positively charged antibody remains in solution, thus separating the two components
3Productivity
If anionic polymer precipitation is used instead of column chromatography, then purification cost decreases and processing capacity increases, but the ability to remove HCP and DNA impurities is insufficient
Solution Approach 1:
The patent changes the pH parameter to below the antibody's pI, which fundamentally alters the charge state of the antibody (making it positive) while impurities remain negative. This parameter change enables the anionic polymer to selectively precipitate impurities without precipitating the antibody, achieving both high productivity and high impurity removal rate
Solution Approach 2:
Instead of the conventional approach of precipitating the antibody and removing impurities from the precipitate, the patent inverts the approach by precipitating only the impurities and keeping the antibody in solution. This inversion is achieved by adjusting pH below antibody pI and using anionic polymer selective precipitation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach achieves high removal rates of HCP and DNA while maintaining high antibody yields, even for low-pI antibodies, and can substitute for conventional column chromatography methods, offering a cost-effective and efficient purification technique.
Implementation Method 1
removing an impurity precipitated by the anionic polymer from the composition, wherein the pI of the antibody is 5.0 to 7.0 and wherein the anionic polymer is polyvinylsulfonic acid (PVS), polyacrylic acid (PAA), or polystyrenesulfonic acid (PSS)
Implementation Method 2
removing an impurity precipitated by the anionic polymer from the composition
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
A composition containing an antibody is prepared in such a state that the composition contains an anionic polymer at pH lower than the pI of the antibody, and impurities insolubilized by the anionic polymer are removed. More preferably, the composition is prepared in such a state that the composition contains an anionic polymer at pH lower than or equal to the pI of the antibody minus one, and impurities insolubilized by the anionic polymer are removed.