Study on Disulfide Bond Formation Protein A in Escherichia coli
大肠杆菌二硫键形成蛋白A（DsbA）研究进展

Disulfide bond formation protein A, DsbA, is one of the important proteins located in E. coli periplasm, which is a foldase facilitating the folding of nascent secreted proteins, especially for those with many pairs of disulfide bonds. The crystal structure and phylogenetic analysis of DsbA and DsbA-mediated protein folding, alternatively in vivo and in vitro, are summarized. Both the extremely low pK_a of Cys~ 30 , about 3.5, and the destabilizing effect of the active site disulfide contribute to its strong oxidizing power. The Cys~ 30 is also considered as the most important residue closely related to its activity using site-directed mutagenesis methodology. DsbA could effectively assist proteins folding, both in vivo coexpressed with the target protein, and in vitro replenished as foldases. Moreover, DsbA also has the chaperone-like activity in the assistant refolding of genetically engineered inclusion bodies.