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I know of Anfinsen's experiments and I'm aware that some denatured enzymes may regain their lost activity through the removal of the denaturant agent. What I'm unaware of is how rare is it for a protein to be able to renature? Can all proteins do that? If not all of them can do it then how rare or common is it to find a protein which can be renatured?

P.S. To avoid answers like "depend on your denaturation process" let us assume that a protein can be renatured if it has been shown to renature in at least one experimental setup.

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This is a very difficult question, and I doubt the answer is known to any satisfying degree of certainty. The best suggestion I have is to look at proteins requiring chaperones to fold. Even that I couldn't find any numbers on, but there might be some papers out there addressing it. –  Alexander D. Scouras May 19 '13 at 0:59

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The answer is more like "It depends on the protein, and the renaturation (or refolding) process." There are a lot of factors that contribute to an individual protein's ability to refold, including size, sequence, secondary structure, amount and type of inter-amino acid links like disulfide bonds, number of subunits, the presence of chaperones/heat shock proteins, and, yes, how it was denatured in the first place (sorry, I couldn't resist). Smaller proteins will refold more easily than larger ones. Hydrophilic proteins tend to refold better than more hydrophobic ones, especially membrane-bound proteins. Multi-subunit proteins/complexes tend to need some help to properly reassemble. Adding in chaperones/heat shock proteins will almost certainly help the process along for all but the smallest and hardiest samples, and will give you better results than just dialyzing all the salts/detergents/chaotropic agents away into PBS. Finally, if you denature by boiling in Laemmli buffer, you're going to have a very difficult time refolding most things, while going from Guanidine HCl to PBS isn't always that bad, depending on what you're looking at.

So, unfortunately the answer is "it depends." You have to remember that the intracellular environment is very complex, and is designed to correctly fold proteins after they're made, and break down misfolded proteins before they can aggregate or cause other damage. There are hundreds of thousands of proteins just in humans, so it is rather difficult to make blanket statements, but for the sake of resistance to damage, many smaller, single-subunit proteins can likely be at least partly to mostly refolded and regain some or all of their original activity. As complexity grows, however, the likelihood of successfully regaining function decreases.

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my impression has been that only relatively small proteins (~10kDa) are readily renatured and used in protein folding kinetics experiments. Its pretty unlikely that anything larger will be useful. Do you have any specific examples of a larger protein that has been refolded by any means, and if so do you think this is a typical result? –  shigeta May 20 '13 at 13:29
    
@shigeta - I was specifically thinking of antibodies (150 kDa, 4 subunits disulfide-bonded to each other). At my previous job we experimented with purifying antibodies by eluting them from an antigen column with varying concentrations of guanidine, then dialyzing directly into PBS. We didn't do any biophysical characterization to look at the extent of denaturation, but in our functional assays they performed similarly to those eluted by the standard (pH-dependent) method. –  MattDMo May 20 '13 at 13:58
    
those antibodies would not be fully denatured. just enough chaotropic agent probably to disrupt protein-protein interactions to get the antibodies off the column. Antibodies have one of the more stable folds and will not usually denature under such conditions. if you did I would be surprised if you could reconstitute a functionally folded protein... imho –  shigeta May 20 '13 at 19:39

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