I understand that I could use guanidinium hydrochloride or urea or TFA to do this. I want to make sure that my protein has completely unfolded before I start the renaturation process. If anybody has done this kind of stuff, your valuable advice would be highly appreciated. The last one seems to be the most potent denaturant, but it can also expensive and acan cause some side effects.
Overnight incubation is more than sufficient.
Frequently the process is complete in under an hour. If your protein contain disulfide bonds, you might need to add 10-100 mM DTT to reduce them. Be advised, that upon renaturation, the protein can misfold.