With DLS you can measure the hydrodynamic radius (Rh) of your protein
which will depend on many things such as viscosity of the medium, shape
of the molecule, etc. Stokes-Einstein law is used for the estimation of Rh.
Normally the maschine parameters are set for a fairly globular ("round")
and for a standard buffer (viscosity). Meaning, you will get a rough
estimate of the MW under the assumption the viscosity of the solution
and shape of macromolecule are within the boundaries set.
Filtering through 0.22 µm will remove aggregates larger than 2200 Å!
Smaller polymers/oligomers will pass through.
From the Z average value you cannot calculate the weight of the
monomer. I assume your sample is polydispers (more than one peak). 71 nm
means the monomer (if monomeric at all) would be clearly larger than
1000 MDa (1000 MDa would give a peak at ±10 nm) and that is very big.
Use the nm-value of the first peak in the spectrum to estimate the MW.
Read the following (PDF freely vailable):
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5425802/
http://www.horiba.com/br/scientific/products/particle-characterization/download-center/webinars/te012/
Good luck,
Jeroen
Am 27.12.18 um 15:57 schrieb amala mathimaran:
Kindly answer this
How to calculate the molecular weight of protein samples using DLS
analysis Size distribution by intensity
The purified protein was subjected to DLS - scattering light intensity
analysis (Horiba nanoparticle analyzer sz-100) and the Z average
result was 71.6nm. from this result how to calculate the molecular
weight of my target protein. Before going to DLS I filtered the
samples in 0.22um so no aggregates present in that samples.
Thanks and Regards
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