Calypso II

Rapid, automated, quantitative characterization of macromolecular interactions

Composition-Gradient Multi-Angle Light Scattering (CG-MALS) employs a series of unfractionated samples of different composition or concentration in order to characterize macromolecular interactions such as reversible self- and hetero-association of proteins, reaction rates and affinities of irreversible aggregation, or virial coefficients. No special modifications - e.g. sample tagging or immobilization procedures - are necessary: samples are entirely in solution.

The primary analysis techniques supported by Calypso are:

  • Strong, specific reversible interactions: Kd (equilibrium dissociation constant) from picomolars to millimolars; stoichiometries of associating complexes; self and/or heteroassociations.

  • Weak, non-specific interactions: self- and cross-virial coefficients

  • Aggregation and other time-dependent reactions: stop-flow kinetics; t (equilibration or relaxation time) from seconds to hours.

  • Zimm plots: concentration gradients for determining MW (weight-averaged molar mass); A2, A3 (second and third virial coefficients); rg (root mean square radius, a.k.a. "radius of gyration")

  • Refractive increment: dn/dc

Calypso's automation enhances productivity by improving repeatability and reliability, while minimizing time and effort. Compared to other techniques for characterizing protein interactions - as well as manual CG-MALS measurements - Calypso provides fast and accurate results.


Drug Discovery:

  • Quantify binding affinity and stoichiometry of enzyme/inhibitor or antibody/antigen interactions
  • Study the impact of small molecules on protein-protein interactions.

Process Improvement:

  • Determine second virial coefficient and adjust buffer parameters to improve formulation stability and viscosity
  • Determine cross virial coefficients to optimize antibody purification and understand the effects of large excipients on formulations.


  • Quantify impact of solvent ionic strength, pH, or excipients on polymerization or protein associations.
  • Measure kinetics of self-assembly and aggregation via rate of change of molar mass and radius of gyration

Biotech R&D:

  • Characterize macromolecular binding affinity and associated complex stoichiometry over a wide range of buffer compositions, time, and temperature scales.


Application Notes:

# Description Download

Does Antithrombin III Block the Action of a Monoclonal Anti-Thrombin Antibody?

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Measuring the Interaction Between Thrombin-α and an Anti-Thrombin Antibody

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Determining the Kinetics of Covalent Thrombin-Antithrombin Association

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Binding Affinity and Stoichiometry of a Multivalent Protein-aptamer Association

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Rapid, Autonomous Lot-to-Lot Comparability of Monoclonal Antibodies with the Calypso

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Measuring Anti-body-Antigen Interactions with the Calypso

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Kinetics of Enzyme-Inhibitor Associations

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Characterization of Heparin Binding to Tau Protein via CG-MALS

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Standard Zimm Plot

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Reversible Self - Association

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Composition Gradient Static Light Scattering: A Powerful Tool for the Detection and Characterization of Reversible Macromolecular Associations

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Continuous Flow for Faster Determinations of Mw and A2

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Characterization of Reversible Hetero-Association with Calypso

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Articles on Calypso


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