Rapid, automated, quantitative characterization of macromolecular interactions with composition-gradient multi-angle light scattering
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 unlabeled and entirely in solution.
Calypso II connected in series to light scattering and concentration detectors
The primary analysis techniques supported by Calypso are:
- Specific reversible complex binding: Kd (equilibrium dissociation constant) from picomolars to millimolars; stoichiometries of associating complexes; self and/or heteroassociations.
- 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. Relative to other techniques for characterizing protein interactions - as well as manual CG-MALS measurements - Calypso provides fast and accurate results.
Applications
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.
Self-assembly/Aggregation:
- 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.
Information on Calypso II hardware
Read some recent articles utilizing the Calypso®:
“Characterizing Interactions at High Protein Concentrations by Static Light Scattering”
