How can I find the denaturing/breaking temperature of a molecule?

[Tanarif]

So essentially, I'm trying to find the temperature at which growth hormone (GH) denatures. I've got a box of it and it says "refrigerate at between 2'C to 9'C". I'm keeping it at room temperature (it's not for use atm), but would like to find out how to know at what temperature GH would break up.

I know GH is made of 191 amino acids, and there's more info on the wiki: https://en.wikipedia.org/wiki/Growth_hormone
Is there like a info sheet I can refer to find the denaturing point of a molecule?

Generally not entirely sure how to go about this, so any help is much appreciated!

 

[aroc91]

I found an article on it, but I don't have access to it.

http://onlinelibrary.wiley.com/doi/10.1002/jps.21386/full

Even so, I came across denaturation temperatures of other proteins like collagen and depending on the state (solid or reconstituted), the temp. can range from 42*C to over 150*C. I would expect GH to be stable at and below physiologic temperature based on that.

 

[Tanarif]

I found an article on it, but I don't have access to it.

http://onlinelibrary.wiley.com/doi/10.1002/jps.21386/full

Even so, I came across denaturation temperatures of other proteins like collagen and depending on the state (solid or reconstituted), the temp. can range from 42*C to over 150*C. I would expect GH to be stable at and below physiologic temperature based on that.

Cheers for that, I've bookmarked it and will purchase and give it a read in a week or two when I'm off from exams. I'll send it over if you're interested.

Collagen and GH are fairly differing in structure, no? It seems about right for collagen as I would imagine it to be a bigger in structure and thus be fair bit stronger too.

 

[Mike H]

Drug and protein formulation can be a subtle science. You don't mention what form the growth hormone is in - solution or solid? The paper linked to above focuses on freeze-dried preparations.

One thing to keep in mind is that activity is generally not guaranteed if not stored under the stated conditions. The case I always remember is that of using light scattering to see whether or not that insulin formulation is too old or stored under undesirable conditions. The proteins haven't fallen apart by any standard, but the desired activity is not maintained.

 

[LudusRex]

I would recommend conducting a thermal denaturation experiment to determine the breaking temperature of GH. This can be done by gradually increasing the temperature of a solution containing GH and monitoring its structural changes using techniques such as spectroscopy or chromatography.

Alternatively, you can refer to the protein's melting temperature (Tm) which is the temperature at which half of the protein molecules are denatured. This information can be found in scientific literature or databases such as the Protein Data Bank (PDB). However, it is important to note that the Tm may vary depending on the experimental conditions and buffer used.

In addition, the stability of a protein can also be affected by factors such as pH, ionic strength, and presence of other molecules. It is recommended to also consider these factors when determining the denaturing temperature of GH.

Overall, the best approach would be to consult with a biochemist or perform your own experiments to accurately determine the denaturing temperature of GH.