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.
Compatible Detectors:
MALS detectors: DAWN HELEOS® or miniDAWN TREOS® Concentration detectors: Optilab® differential refractometer, UV/Vis absorption or similar
Syringe Pumps:
3, dc-servo motor; 4-port distribution valve on each pump
Syringe Volumes:
12.5 μL-12.5 mL (1 mL syringes supplied as standard)
Degasser Channels:
1 per pump, 100 μL internal volume
Pressure Limit:
1-mL syringes: 200 psi
0.5-mL syringes: 350 psi
Auxiliary Inputs/Outputs:
Autoinject out, injector valve control, recycle valve control digital and analog I/O for specific applications
Mw: ±5%
A2: ±0.5x10-4 mol⋅mL/g² for sample molar mass of 50-100 kDa
log(Kd): ±0.3
Range of Measurement:
Equilibrium Dissociation Constant, Kd: 100 pM-1 mM typical for 100 kDa molecules (actual range varies with molecular weight and association stoichiometry) Association Stoichiometry Models: arbitrary self + hetero-assocation models, equivalent binding site for self- and hetero-association, aggregation of complexes, incompetent fractions
Power Requirements:
100-240VAC
Host PC Requirements:
2.8 GHz or better processor, 1 GB RAM
Ethernet connection for HELEOS/TREOS communications
Software Compatibility:
Microsoft Windows® XP, Vista or Windows 7
Dimensions:
37 cm (W) x 35 cm (H) x 58 cm (D)
* Specifications subject to change without notice.
Wyatt Technology is the recognized leader in light scattering instrumentation and software for determining the absolute molar mass, size, charge and interactions of macromolecules and nanoparticles in solution. These tools include: in-line multi-angle static light scattering, high-throughput dynamic light scattering, differential refractometry, electrophoretic mobility, differential viscosity, field flow fractionation and automated composition gradients.
