Recombinant von Willebrand Factor Mass Spectrometry Calibration
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Solution Overview
Problem
Current mass spectrometry methods are limited in determining the molecular weight of analytes with masses greater than 100 kDa due to the lack of well-defined protein/glycoprotein standards, particularly for molecules above 150 kDa, leading to decreased accuracy when analytes have masses outside the range of known standards.
Innovation Solution
Recombinant von Willebrand factor (rVWF) is used as a molecular weight marker, allowing for the calculation of high molecular weight analytes by measuring the mass spectrum of rVWF multimers, which can be prepared to match the suspected mass of the analyte, enabling accurate calibration of mass spectrometry techniques for molecules up to 5,000 kDa or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional protein standards (e.g., immunoglobulins) are used for mass spectrometry calibration, then the method is simple and well-established, but the accuracy decreases for analytes with molecular weights greater than 150 kDa
Solution Approach 1:
The patent changes the molecular weight parameter of the calibration standard from conventional proteins (150 kDa max) to rVWF multimers (200-5000+ kDa). By producing rVWF with controlled multimerization, the standard's molecular weight parameter is adjusted to match high molecular weight analytes, thereby improving measurement accuracy for these substances.
Solution Approach 2:
The rVWF standard is segmented into defined multimeric units (dimers, multimers) with known molecular weights. Each multimer consists of a specific number of monomeric units linked by disulfide bonds, creating a segmented structure that provides multiple calibration points across a wide molecular weight range, improving both accuracy and versatility.
2Measurement precision
If rVWF multimers are produced as molecular weight standards, then accuracy for high molecular weight analytes improves, but the complexity of producing well-defined multimers increases
Solution Approach 1:
The patent applies preliminary action by incorporating a specific pro-peptide sequence at the N-terminus of the rVWF monomer during production. This pro-peptide facilitates controlled multimerization through disulfide bond formation, ensuring that multimers are formed with defined stoichiometry before the calibration standard is used. This preliminary structural design simplifies the overall production of well-defined multimers.
Solution Approach 2:
The disulfide bonds act as intermediaries that link rVWF monomers into dimers and multimers in a controlled manner. This chemical intermediary mechanism ensures consistent and reproducible multimer formation, reducing production complexity by providing a natural self-assembly pathway rather than requiring complex purification and assembly protocols.
3Stability of the object's composition
If plasma-derived VWF is used as a standard, then the standard reflects native structure, but batch-to-batch consistency and cost-effectiveness are compromised
Solution Approach 1:
The patent creates a recombinant copy of native VWF that replicates its essential structural features and multimerization properties. The rVWF is produced in a controlled system (insect or mammalian cells) that copies the native protein's sequence and post-translational modifications, providing batch-to-batch consistency while maintaining structural authenticity. This copying approach eliminates variability associated with plasma donation and processing.
Solution Approach 2:
The rVWF production system uses self-service by utilizing the host cell's (insect or mammalian cell) natural protein folding and glycosylation machinery to produce correctly structured VWF multimers. The system self-assembles the multimers through programmed disulfide bond formation, eliminating the need for complex external processing and purification steps that would compromise batch consistency.
Data Source
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AI summary
Methods for determining molecular mass of at least 150 kDa of an analyte of interest using MALDI mass spectrometry in combination with a recombinant von Willebrand factor (rVWF) molecular weight marker are disclosed. More specifically, monomeric and multimeric rVWF are used for external and internal calibration of mass spectra applied for analytes having high molecular weights above 150 kDa.