It's not clear to me what you mean by "if it found to be thermostable in optimum temperature studies". In terms of finding the thermostability, say the Tm, there are a variety of ways to do this. One of the easiest would be using circular dichroism (CD) where you follow the ellipticity at a particular wavelength (often 222nm) as a function of temperature. If your protein unfolds cooperatively you should get a sigmoidal curve with the Tm being the point at which you have 50% folded and 50% unfolded. An advantage to using CD is that a simple scan at low temperature can give you additional information such as the secondary structure content or an indication of whether your protein is actually folded.

If you have buried tryptophans in your protein you could use intrinsic fluorescence as a function of temperature as another relatively easy technique. More detailed thermal stability information can be obtained using differential scanning calorimetry (DSC).

Note that if you have a particularly stable protein, say from a thermophile, you may not be able to get the Tm directly - the above methods are typically (but not always) limited to measuring Tm's below 100C.

It's not clear to me what you mean by "if it found to be thermostable in optimum temperature studies". In terms of finding the thermostability, say the Tm, there are a variety of ways to do this. One of the easiest would be using circular dichroism (CD) where you follow the ellipticity at a particular wavelength (often 222nm) as a function of temperature. If your protein unfolds cooperatively you should get a sigmoidal curve with the Tm being the point at which you have 50% folded and 50% unfolded. An advantage to using CD is that a simple scan at low temperature can give you additional information such as the secondary structure content or an indication of whether your protein is actually folded.

If you have buried tryptophans in your protein you could use intrinsic fluorescence as a function of temperature as another relatively easy technique. More detailed thermal stability information can be obtained using differential scanning calorimetry (DSC).

Note that if you have a particularly stable protein, say from a thermophile, you may not be able to get the Tm directly - the above methods are typically (but not always) limited to measuring Tm's below 100C.

I totally agree with the answer of Trevor Creamer. It depends on your particular protein, but I used fluorescence to detect conformational changes by buried Trp and it works pretty well. Of course, CD and DSC are also very powerful techniques.

Far-UV CD gives stability of secondary structure, Near-UV CD gives stability of tertiary structure, Trp intrinsic fluorescence gives the change in burried Trp environment. DSC gives info about the global protein stability (secondary + tertiary + quarternary). TUG-PAGE gives info about the global unfolding of proteins. Other techniques include extrinsic fluorescence using ANS or nile-Red dye and Dynamic fluorescence quenching (DFQ) using acrylamide which can determine relative flexibility of two homologous or varient proteins.

Seems very interesting!!!

As suggested by Khawar Siddiqui, you can use circular dichroism (CD) spectroscopy for determining the thermal stability of your protein. Additionally you can also determine the protein refolding capacity, approximate 2ndary structure determination with this method. But limitation of this technique is, you need to have quite pure protein to perform all these measurements

Just browsing David Minde paper, I think you may be able to apply this new technique to determine the stability of your protein which may not be pure.

In deed, worthy discussion. In my opinion, the optimum temperature study and study on the thermostability of enzyme are different but may be taken together for coordination study as far as enzyme kinetics of an enzyme of interest is concerned.

There are excellent protocols for evaluating thermal stability of proteins with Thermal Shift. This technique can be done using a real-time thermocyclers and with protein dyes as Sypro-Orange to keep track of protein conformational changes.

Absolutely agree with Carlos. This produces excellent quality data and can define Tm to within a fraction of a degree.