AAV Capsid Protein SEC-MS Characterization Without Ion-Pair Suppression
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Solution Overview
Problem
Existing methods for characterizing adeno-associated virus (AAV) capsid proteins using liquid chromatography-mass spectrometry are suboptimal due to the use of strong ion pairing agents that suppress MS signal intensity and cause protein backbone hydrolysis, making them unsuitable for sensitive detection of low-concentration AAV samples.
Innovation Solution
A method involving size exclusion chromatography under a denaturing mobile phase, using acetonitrile, formic acid, and ammonium formate, coupled with fluorescence and mass spectrometry, to separate and characterize AAV capsid proteins without strong ion pairing agents, enabling sensitive detection and analysis of VP1, VP2, and VP3 stoichiometry and heterogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strong ion pairing agents (DFA or TFA) are used in LC-MS for separation of AAV capsid proteins, then protein separation is achieved, but MS signal intensity is suppressed and protein backbone hydrolysis occurs
Solution Approach 1:
The patent changes the chemical parameters of the mobile phase by replacing strong ion pairing agents (DFA, TFA) with formic acid and ammonium formate. This parameter change reduces ion pairing strength, thereby maintaining MS signal intensity while preventing protein backbone hydrolysis. The denaturing mobile phase composition is optimized to achieve both separation and sensitive detection.
Solution Approach 2:
The patent introduces formic acid and ammonium formate as intermediary substances that mediate between the separation process and MS detection. These intermediaries provide sufficient ion pairing for chromatographic separation while being volatile enough to not suppress MS signal, thus resolving the conflict between separation and detection sensitivity.
2Quantity of substance
If conventional LC-MS methods are used for characterizing AAV capsid proteins, then separation is achieved, but sensitive detection of low concentration samples is compromised
Solution Approach 1:
The patent optimizes the mobile phase parameters to be compatible with both separation and sensitive MS detection. By using formic acid (1%) and ammonium formate (5-10 mM) instead of conventional strong ion pairing agents, the method maintains low sample concentration requirements while achieving high detection sensitivity through reduced ion pairing interference.
3Measurement precision
If size exclusion chromatography is used under denaturing conditions, then protein components are separated based on size, but protein structure is disrupted
Solution Approach 1:
The patent uses a denaturing mobile phase containing formic acid and ammonium formate that disrupts non-covalent interactions in proteins while maintaining separability. The denaturing conditions allow size-based separation of protein components (VP1, VP2, VP3) without requiring extreme conditions that would cause aggregation or degradation, thus achieving both separation and compositional stability.
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
The method provides high sensitivity and accuracy in separating and identifying AAV capsid proteins, allowing for effective stoichiometry determination and detection of post-translational modifications, while also enabling detection of nucleic acids, and is applicable to various AAV serotypes and recombinant vectors.
Implementation Method 1
subjecting the sample to size exclusion chromatography under a denaturing mobile phase to separate the protein components of the viral capsid
Implementation Method 2
subjecting the sample to size exclusion chromatography under a denaturing mobile phase
Implementation Method 3
fluorescence is detected using an excitation wavelength of 280 nm, and an emission wavelength of 348 nm
Implementation Method 4
detecting the protein components by fluorescence to determine the relative abundance of the protein components separated by SEC, thereby determining the stoichiometry
Data Source
AI summary
The present disclosure provides methods and systems for characterizing protein components of a viral capsid of a viral vector. In particular, the methods comprise subjecting a viral vector to size exclusion chromatography under a denaturing mobile phase to separate the protein components. Further, the present disclosure also provides methods for identifying and/or characterizing at least one low molecular weight (LMW) antibody species in a sample, wherein the method comprises subjecting the sample to size exclusion chromatography (SEC) column under a denaturing mobile phase to separate the LMW antibody species, and detecting the LMW antibody species by mass spectrometry to identify and/or characterize at least one LMW antibody species.