The most basic method is validation via SDS-PAGE. While proteins can migrate at a different size than expected, for various reasons, it generally gives you a good idea of the approximate molecular weight. One step up might be analytical gel filtration, or dynamic light scattering, to validate the state in solution, e.g. in case you expect multimers.

Should you have an activity assay on hand, this is of course the best way to provide an estimate of the quality of your purified protein.

There is a plethora of methods to do quality control for proteins, but these are (in my opinion) the most accessible ones.

Hi,

What do you mean by 'intact'? And what is the (approximate) molecular weight of the protein? Does it comprise multiple subunits and do you expect modifications, like glycosylation, on it?

I'd suggest to find out if you can check the functionality of your protein, i.e. ligand binding, catalytic activity, etc.

Another method to consider could be native mass spectrometry.

Hope this helps.

There are several methods and procedures that can be used to assess the integrity of a purified protein. Here are some commonly employed techniques:

SDS-PAGE (Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis), Western Blotting, Mass Spectrometry, Circular Dichroism (CD) Spectroscopy, Size-Exclusion Chromatography (SEC),Analytical Ultracentrifugation