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Theory and Practice of CG-MALS Book Chapter

Curious to learn how light scattering provides label-free, immobilization-free, first-principles characterization of macromolecular interactions? Download this open-access publication!


Protein Interactions, J. Cai and R.E. Wang (ed.), InTech, 2012

Chapter 20: Characterization of Protein-Protein Interactions via Static and Dynamic Light Scattering

By Daniel Some and Sophia Kenrick

Macromolecular interactions play key roles in a host of scientific and biotechnological studies—from basic biomolecular research to protein therapeutic R&D. Light scattering measurements quantify these phenomena without tagging, immobilization, or other sample modifications that can potentially skew the interaction of interest. Composition Gradient Multi-Angle static Light Scattering (CG-MALS) and Composition-Gradient Dynamic Light Scattering (CG-DLS) determine a variety of quantitative interaction parameters, including equilibrium dissociation constants (KD), stoichiometry, virial coefficients (A2) and reaction rates. Recent advances in instrumentation and technique simplify and automate measurements, resulting in hands-off operation with excellent repeatability.

The first half of the chapter reviews the theory and practice of CG-MALS and CG-DLS. The second half focuses on a range of applications, including:

  • Protein self-association as a function of ionic strength, pH, and other excipients
  • Hetero-association between two proteins with various stoichiometries
  • Self-assembly of multivalent protein complexes
  • Dissociation kinetics
  • Nonspecific attractive and repulsive interactions
Figure 1: Quantification of self (a) and hetero-associations (b-c) by CG-MALS.

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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.

Wyatt's line of multi-angle static light scattering products couple to size exclusion chromatography (SEC-MALS), field-flow fractionation (FFF-MALS), and stop-flow composition-gradient systems (CG-MALS). Our dynamic light scattering (DLS) products operate in traditional cuvette as well as on-line and automated, high-throughput modes. We also offer unique instruments for electrophoretic light scattering (MP-PALS), differential refractometry, and differential viscosity.

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