Protein refolding is, particularly, very important to purify proteins from inclusion bodies. There is no a universal refolding buffer formulation that can be used for all proteins. It is usually important to optimize a refolding buffer condition for each proteins. One of the buffer condition that is critical for maintaining proteins in their soluble and stable forms during refolding is the pH of the buffer. An optimum pH range can be identified for each proteins depending on their PI values. The pH of the buffer that is 2 to 3 units above or below the PI value of the protein can be important to maintain the proteins in their soluble and stable forms.

Buffer additives are also crucial components of protein refolding formulations. For example, L-Arginine is one of the most commonly used additives to prevent protein aggregation during the refolding process. There are also numbers of other additives that are used to solubilize and stabilize proteins during the refolding of proteins.

The production or elimination of disulfide bonds will certainly depend on solution's pH. Nonetheless for any of those processes to occur you need a molecule willing to receive or donate electrons. If you start with no disulfide bonds and want to produce them, you need add a molecule to take some electrons. 

Cystein/cystine or reduced/oxidized glutathion are used as redox shuttle, to not only drive the formation of disulfide bonds by creating a net oxidizing environment, but to allow wrongly formed disulfide bonds to be reduced again, driving the system to the most stable form rather than allowing it to be trapped into the kinetically favored form (Some wrong disulfide bonds my form quickly, because the cysteins are very accessible). The redox shuttle assumes the function which in vivo is performed by disulfide isomerases. The kinetics of disulfide formation is highly pH-dependent. Arginine mainly is used to prevent aggregation (Biotechnol. Prog.2004,20,1301−1308,http://onlinelibrary.wiley.com/doi/10.1021/bp0498793/epdf)