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Characterizing protein-protein interactions with mass photometry

Measure protein interactions with mass photometry


Protein interactions play critical roles in various biological processes, but their complexity often poses challenges. 


Mass photometry is a bioanalytical method for protein-protein interaction studies with single-molecule precision. It is a fast and label-free technology, which can measure the molecular mass of proteins in solution, within the 30 kDa – 5 MDa range. In the study of protein interactions, mass photometry measurements can provide a detailed overview of the binding partners present, the complexes they form, the relative abundance of each species and the binding affinity of each protein.

Depiction of a protein-protein interaction


In this application note, mass photometry is used to characterize interactions between Immunoglobulin G (IgG) antibodies of different origin species (human and bovine) and protein A.

How to assess sample heterogeneity and quality?

Mass photometry mass histograms of protein controls (IgG, protein A) for purity assessment.

Mass photometry not only enables the study of protein interactions but also serves as a valuable tool to assess the purity and quality of protein control samples. By measuring the mass distribution of individual proteins in a sample, it can identify protein aggregation or oligomerization, ensuring accurate interpretation of the results.

Image: Mass photometry can assess sample heterogeneity. For experimental details, download the app note

How to determine protein binding affinity with mass photometry?


Mass photometry is a powerful bioanalytical tool that assesses the dynamics and strength of protein-protein interactions by directly measuring the mass and relative abundance of individual proteins and their complexes in solution. It enables the calculation of equilibrium dissociation constants (KD) for each interaction, providing quantitative information about their protein binding affinity. By comparing the complexes formed between protein A and human IgG versus bovine IgG, mass photometry demonstrated differences in affinity between the two interactions.

To learn how mass photometry can help measure protein interactions and binding affinities

Quantifying protein binding affinities with mass photometry

Quantifying protein binding affinities using mass photometry.png

Read this application note to learn how you can use the TwoMP mass photometer to characterize protein-protein interactions, quickly and easily. Discover how you can determine the relative abundance of each protein and the complexes they form in solution, using this label-free bioanalytical tool. Learn also how you can use the mass photometry measurements to calculate the equilibrium dissociation constant (KD) for each interaction.


Additional resources​


Monitoring aggregation levels of biosimilar mAbs using mass photometry and SEC

Learn how mass photometry compares with size-exclusion chromatography in measuring aggregation levels of monoclonal antibodies such as trastuzumab, and several trastuzumab biosimilars. Discover the pros and cons of each technology and the factors that should be considered when analyzing and comparing data generated by these different techniques.

Image depicting Webinar title - Monitoring aggregation levels of biosimilar mAbs using mass photometry and SEC
Image of a scientist using the TwoMP Auto mass photometer. Title of the webinar "Automated Mass Photometry: Easing the Path to Biomolecular Characterisation" is superimposed on the image.


Automated Mass Photometry: Easing the Path to Biomolecular Characterisation

Learn how you can apply automated mass photometry in your protein characterization workflow — such as screening and titration assays. Discover how automation and the associated improvement in reproducibility can make biomolecular characterization with mass photometry even easier

To discuss how mass photometry can be applied in your protein characterization workflow

More Application Notes

Browse through our catalogue of application notes highlighting some recent case studies featuring mass photometry.

Investigating lentivirus titer with macro mass photometry


Mass photometry supports membrane protein purification protocols 

Characterizing protein oligomerization with automated mass photometry

Quantifying heterogeneous AAV capsid loading using mass photometry

Download the application note

Download the app note
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