Expand Your Characterization Capabilities
Our detectors for multi-angle light scattering and refractive index represent the leading technology in their categories. When combined, they create an all-new level of capability that dramatically expands your characterization capabilities.
DAWN® HELEOS® II
The most sensitive MALS detector available, anywhere. Incorporates detectors at 18 angles to determine molar masses from 200 Da to 1 GDa and radii from 10 – 500 nm.
A unique on-line differential refractometer for measuring concentration of any macromolecule, regardless of chromophores. The high-concentration Optilab accommodates protein concentration up to 180 mg/mL.
Molar mass is the key to identifying proteins, their oligomers or complexes, yet all too many protein researchers rely on simplistic, invalid analysis of molecular weight by SDS-PAGE or traditional size exclusion chromatography (SEC). These techniques invoke assumptions of conformation and ideal matrix interactions that may fool scientists with ambiguous or completely incorrect results, leading to fundamentally inaccurate interpretation of their data for scientific publications.
Multi-angle light scattering coupled with SEC (SEC-MALS) provides accurate molecular weight determination of proteins, oligomers and complexes, regardless of conformation or non-ideal column interactions. That's because SEC-MALS constitutes a rigorous, first-principles analysis of molar mass that does not rely on retention time or calibration with reference molecules. The only function of the SEC column is to separate molecules by size, while MALS determines molar mass of eluting proteins independently.
Conjugated and Membrane Proteins
Membrane proteins solubilized with detergent are particularly difficult to analyze by traditional techniques or even by mass spectroscopy because of the surfactant micelle surrounding the protein. Denaturing SDS-PAGE dissociates native oligomers and precludes their identification, while cross-linked mass spectroscopy can create oligomers that do not exist in solution.
Likewise, heavily glycosylated proteins cannot be represented by reference standards or common models for globular proteins, and so are not amenable to analysis by traditional techniques.
These challenges are met by multi-angle light scattering coupled with SEC (SEC-MALS) which can distinguish between a protein and its associated detergent or carbohydrate by combining data from three detectors downstream of SEC separation: UV, MALS and differential refractive index (dRI). ASTRA's Conjugate Analysis algorithm calculates the molar masses of both the proteinaceous component and the conjugated or micellar component. The true oligomeric or complexated state of the protein, as well as the degree of glycosylation, are determined unambiguously.