An analysis of the protein folding characteristics of the eukaryotic protein folding enzyme protein disulfide isomerase (PDI) led to a study of the minimally sufficient motif for catalytic activity of that enzyme as well as the prokaryotic enzyme thioredoxin. Based on such study, a model for this catalytic activity was developed which was used to predict what non-protein catalysts might substitute for this enzymatic activity. Based on this analysis, it was predicted that a small molecular weight dithiol molecule having a pK.sub.a of less than about 8.0 and an E.degree.' of more than about -0.25 V could catalyze the formation of proper disulfide bonds in a eukaryotic protein. Subsequently, it was verified that such a dithiol, such as the exemplary molecule N,N'-bis(2-mercaptoacetyl)-1,2-diaminocyclohexane (BMC), is capable of catalyzing the proper formation of disulfide bonds, and the proper folding of proteins, both in vivo and in vitro. This permits a small organic molecule to be substituted for an enzymatic system in protein synthesis.