Folding of small disulfide-rich proteins: clarifying the puzzle

Abstract

The process by which small proteins fold to their native conformations has been intensively studied over the last few decades. In this field, the particular chemistry of disulfide bond formation has facilitated the characterization of the oxidative folding of numerous small, disulfide-rich proteins with results that illustrate a high diversity of folding mechanisms, differing in the heterogeneity and disulfide pairing nativeness of their intermediates. In this review, we combine information on the folding of different protein models together with the recent structural determinations of major intermediates to provide new molecular clues in oxidative folding. Also, we turn to analyze the role of disulfide bonds in misfolding and protein aggregation and their implications in amyloidosis and conformational diseases.2

The Mitochondrial Intermembrane Space Oxireductase Mia40 Funnels the Oxidative Folding Pathway of the Cytochrome c Oxidase Assembly Protein Cox19

“…The physiological relevance of those results were recently confirmed in mammalian cells in vivo, where the GSH pool was shown fundamental for the efficient import of Cox19 and other Mia40 substrates (22). Low amounts of reducing agents are known to increase oxidative folding rates acting as thiol catalysts by counteracting the accumulation of partially oxidized non-native isomers (23). In Fig.…”

Characterizing the Tick Carboxypeptidase Inhibitor

“…These studies revealed that both species comprise three native disulfide bonds in one domain and no disulfide bonds in the other domain. IIIa: Cys 3 Table 1 and the MS spectra in the supplemental materials.…”

“…Understanding the sequence of folding events in proteins may not only help to predict protein structures from amino acid sequences but also provide invaluable information to a variety of related fields, such as protein design or protein misfolding associated with pathological diseases (1,2). A number of studies concerning folding have been focused on small, disulfide-rich proteins, given that the chemistry of disulfide bond formation allows the trapping and subsequent characterization of the folding intermediates that accumulate, something difficult to attain with disulfide-free proteins (3,4). In oxidative folding, reduced and denatured proteins are allowed to recover both its native disulfide bonds and native structures in the absence or presence of redox agents.…”

A Novel Plant Protein-disulfide Isomerase Involved in the Oxidative Folding of Cystine Knot Defense Proteins

“…Fig. 7 summarizes the OaPDI-assisted folding pathways of the linear and cyclic peptides in the form of a folding funnel diagram (41,42). After 24 h, the peptides are mainly oxidized and have folded either into their native disulfide connectivities, which occupy the lowest energy levels in the folding funnel or are trapped in higher energy wells as nonnative three-disulfide species.…”