Hi Prem,

One of the best methods for this is analytical ultracentrifugation. We (Newcastle University Protein and Proteome Analysis) provide this as a service. Do get in touch, if you are interested.

Best wishes,

Achim

Yes.... for sure you can use DLS and in the combination with Gel filtration you will get an rough idea about the conformation of the protein in the solution, But the best solution is to do SAXS (Small angle x-ray scattering) or Analytical ultra centrifugation.

Good luck

Eswar

From your description it sounds as if DLS would be an ideal tool to check the oligomeric state of your protein. If your protein is well-purified and homogenous it should be possible to determine its oligomeric state from batch DLS run in a cuvette. There is an oline calculator that can predict the estimated size of your protein from its molecular weight (see www.malvern.com/calculator which also shows the minimum concentration you would need in order to measure enough scattering signal for repeatable data quality). If you have DLS data already, you could use the calculator to confirm that your measured results agree with the prediction of the empirical globular protein model.

Here are a few words of caution though:

- if your DLS result shows a high polydispersity, i.e. a broad peak, then this could be due to the presence of a range of oligomers (most likely) or due to non-globular shape of your protein

- if your DLS result shows a significant contribution from some very large aggregates, try to filter or centrifuge. If the high molecular weight component remains, this could lead to potential problems with data interpretation for AUC and SAXS.

DLS is a fast and simple tool to get a quick idea of the homogeneity and approximate oligomeric state of your protein in solution. It is very likely that someone in a department nearby has access to DLS, so do give it a try. You can always do AUC or SAXS later for a more thorough investigation if required. Good luck!

acctually, static light scattering is the method of choise; DLS is a hydrodynamic measurement of SIZE (as is size exclusion chromatograph) and cannot distinguish between effects of oligomerization or extended shape or both on changes in protein size.