Molecular weight

Looking at apparent molar mass

What is measured?

The measured quantity is the molecular weight of macromolecules or protein solution samples.

Range of molecular weight accessible from SAXS measurement:

  • 1 to 300 kDa

Figure 1. Scattering data acquired on lyzosyme in acqueous solution (top) and the corresponding Guinier fit of the low q data points (bottom).

In the absence of aggregation effects, a simple analysis allows one to estimate the mean size of the scatterers, supposedly similar in shape and size. In the low q range, the scattering of globular objects is well described by the Guinier law.

Samples

Typical samples for this measurement are:

  • Globular nano-objects in solution, in particular globular proteins

Methods & standards

Standards & methods used for molecular weight determination:

  • Guinier analysis
    Ref: A. Guinier, G. Fournet Small-Angle Scattering of X-rays. John Wiley, New York, 1955

XSACT analysis software implements the above method.

Advantages of SAXS

Why use SAXS for molecular weight determination ?

  • SAXS is a non-destructive method, allowing to study samples in their bio-chemical environment.

  • SAXS does not require a reference protein for measurements

  • Molecular weight measurements require absolute intensity measurement of scattering. With Xenocs SAXS equipment, this is possible without the need for intensity calibration.

Products

All these measurements are possible directly in your lab.

Nano-inXider

Smart nanoscale characterization

BioXolver

Accelerate your biostructural research

Xeuss 3.0

The Next Generation
(GI)SAXS/WAXS/USAXS beamline for the laboratory