Diversity of chemical mechanisms in thioredoxin catalysis revealed by single-molecule force spectroscopy

作者：Perez Jimenez Raul^*; Li Jingyuan; Kosuri Pallav; Sanchez Romero Inmaculada; Wiita Arun P; Rodriguez Larrea David; Chueca Ana; Holmgren Arne; Miranda Vizuete Antonio; Becker Katja; Cho Seung Hyun; Beckwith Jon; Gelhaye Eric; Jacquot Jean P; Gaucher Eric; Sanchez Ruiz Jose M; Berne Bruce J; Fernandez Julio M

来源：Nature Structural & Molecular Biology, 2009, 16(8): 890-U120.

DOI：10.1038/nsmb.1627

Thioredoxins (Trxs) are oxidoreductase enzymes, present in all organisms, that catalyze the reduction of disulfide bonds in proteins. By applying a calibrated force to a substrate disulfide, the chemical mechanisms of Trx catalysis can be examined in detail at the single-molecule level. Here we use single-molecule force-clamp spectroscopy to explore the chemical evolution of Trx catalysis by probing the chemistry of eight different Trx enzymes. All Trxs show a characteristic Michaelis-Menten mechanism that is detected when the disulfide bond is stretched at low forces, but at high forces, two different chemical behaviors distinguish bacterial-origin from eukaryotic-origin Trxs. Eukaryotic-origin Trxs reduce disulfide bonds through a single-electron transfer reaction (SET), whereas bacterial-origin Trxs show both nucleophilic substitution (S(N)2) and SET reactions. A computational analysis of Trx structures identifies the evolution of the binding groove as an important factor controlling the chemistry of Trx catalysis.

• 出版日期2009-8