Cyclic 5-Membered Disulfides Are Not Selective Substrates of Thioredoxin Reductase, but Are Opened Nonspecifically by Thiols

Abstract

<div> <div> <div> <p>The cyclic five-membered disulfide 1,2-dithiolane has been used as the key element in numerous chemical biology probes. Contradictory views of this disulfide motif populate the literature: some reports describe it as being nonspecifically reduced, others as a highly specific substrate for thioredoxin reductase (TrxR). We show that 1,2-dithiolanes are nonspecifically reduced by a broad range of thiol reductants and redox-active proteins, and that their cellular performance is barely affected by TrxR inhibition or knockout. We conclude that inhibitor screenings and probe designs treating 1,2-dithiolanes as TrxR-selective substrates should be treated with caution and previous interpretations may need careful re-evaluation. Considering ring-opening polymerisation, and stringently interpreting assays involving the thiophilic gold-based inhibitor auranofin, are critical to assess 1,2-dithiolane’s true behaviour. We present an approach to control against assay misinterpretation with reducible probes, to ensure that future TrxR-targeted designs are robustly evaluated for selectivity, and to better orient redox probe research in the future. </p> </div> </div> </div>

Thiol-Mediated Uptake

“… 108 − 110 The puzzling relation of specific thioredoxin labeling with 34 and thiol-mediated uptake is being addressed by Thorn-Seshold and co-workers. 111 …”