Detailed biophysical characterization of biomolecules in solution
Instruct has 4 centres offering Multi Angle / Dynamic Light Scattering (MALS) across Europe. Navigate the map and click on the pins to discover centres near you.
The availability in Instruct of the most advanced instruments for Multi Angle Dynamic Light Scattering (MALS) combined quasi-elastic light scattering (QELS) detectors allows the user to carry out a detailed biophysical characterization of biomolecules in solution. The measure of the intensity of laser light, scattered at different angles by macromolecules passing through the flow cell and the analysis of the autocorrelation function of the laser light fluctuations allow the calculation of: the concentration of the biomolecules in solution, the molecular weight, the radius of gyration (rg), the translational diffusion coefficient (Dt) and the related hydrodynamic radius (rh). The technique is extremely sensitive and provides information on the shape and aggregation state of the biomolecules in solution.
In a classical experiment, the proteins present in solution are separated using size exclusion chromatography and the hydrodynamic radius versus elution time for the proteins is then determined. Even for molecules with rg below the angular variation detection limit of 10 nm, the simultaneous measurements in the integrated MALS-QELS system provide complete results for rh as well as molar mass. Although molecular weights can also be determined via mass spectrometry and analytical centrifugation, only light scattering and analytical centrifugation monitor the properties of macromolecules in solution and provide information about possible oligomeric states. The comparatively short time of a DLS measurement greatly facilitates carrying out the multiple studies that may be needed to determine the impact of protein concentration, ligands, and pH. The QELS detector may be used also in a batch mode with special 10 µL cuvettes.
The combined MALS-QELS system can be used to analyze:
Typical sample injection volume is 50-100 µL with a protein concentration that is related to the mass of the protein itself. For a 50 kD protein, 0.5 mg/mL are required. Samples must be absolutely free of particles, aggregates and bubbles. Therefore, the sample must be filtered before injection with low protein binding filters of 0.02 µm. Different buffers can be used and several components are tolerated after system equilibration.
All of the components required for MALS-QELS analysis are available at the facility: