Oxidative Protein Folding

Abstract

Oxidative protein folding is the process by which a protein recovers both its native structure and its native disulphide bonds. Disulphide bonds are vital for the correct folding of many secreted proteins, such as insulin, albumin, tissue plasminogen activator and antibodies. The formation of a disulphide bond between two cysteine residues is a rate‐limiting step of the folding process. Therefore, living cells contain proteins that catalyse this reaction (DsbA, protein disulphide isomerase (PDI), Mia40). Pathways that form disulphide bonds have now been unraveled in the bacterial periplasm, the endoplasmic reticulum and the mitochondrial intermembrane space. These pathways have in common to form a relay that channels the electrons released upon cysteine oxidation to a final electron acceptor. Key Concepts: Disulphide bond formation is required for the correct folding of many secreted proteins. Disulphide bond formation is a catalysed process in vivo . Pathways of disulphide bond formation are found both in prokaryotes and in eukaryotes. Pathways of disulphide bond formation form a relay that channels the electrons away from the substrate protein to a final electron acceptor. Pathways of disulphide bond formation involve a direct disulphide donor and a disulphide generator. Formation of native disulphides in proteins with multiple cysteine residues involves a disulphide isomerase. A disulphide formation pathway and a disulphide isomerisation pathway co‐exist in bacteria such as Escherichia coli . Protein disulphide isomerase (PDI) catalyses both disulphide bond formation and disulphide bond isomerisation in the endoplasmic reticulum.