Hi There are 

Hi Prabhadevi, you could use biophysical techniques like circular dichroism, differential scanning fluorimetry or dynamic light scattering, if you have access to them. If not, you could just check the stability over time, by taking e.g. 10 micrograms per day out, centrifuge them and take the supernatanf for SDS-PAGE analysis ( over 10 days, all on one gel) and compare the strength of the bands and check for possible degradation/aggregation. If you have an activity assay, ckeck for specific activity. Good jck, Magdalena

Your test looks for aggregation.  It is only sensitive to very large aggregates, depending on ho long you spin and how fast. But it will tell you how much protein is left behind.  Dynamic light scattering is fast, non-destructive method that you might try before and after spinning your sample.  Pure protein will have a characteristic diffusion coefficient proportional, roughly, to mass.  Aggregates scatter light much more strongly.    By checking before spinning, you see if there is a time dependent change in aggregation state.  By testing again after spinning, you see if spinning removed contaminants and left you with a sample that resembles your starting material.

Thank you all for answering my question. I will definitely try out all the possible ways you have all suggested to me.

Thanks!

What do you mean with stability? Usually this means hal-life in vivo, but I understand this is not what you mean. Therefore I think the answer by Magdalena Schacherl will be useful.

Best

Sandro Vitale

Determine the aggregation index by taking absorbence at 280 nm and 350 nm on spectrophotometer (refer std. formula for calculating aggregation index). This will give you colloidal stability of your protein. Do not spin if the protein is already in solution). Conformational stability, just take the Fluorescence (before and after) and compare the intensity and lambda shift.  These are best accepted ways to understand stability of protein. Other method exist but requires sophisticated instruments and are cumbersome.

Thank you all

Will test my proteins stability as suggested by you

How large is your protein? What types of stabilizing agents have been used during its purification? Before you perform any of the tests recommended, you might want to ensure that your protein is free of all stabilizing agents and inhibitors from earlier steps. What are your thoughts? Do you know the amino acid sequence and composition of your protein? If so, have you performed any computational analyses of the sequence? Have you performed an BLAST search and read about other proteins with which your protein may be homologous? I would recommend that you use such information to assist you in your experimental design to test the stability of your protein. Good luck!

My protein is small, around 11kDa in size. I know the sequence and its amino acid composition. I have tested other homologous proteins but they seem to be stable. But my protein is highly charged.