Enzyme

1.8.1.9 - Thioredoxin-disulfide reductase

Alternative Name(s)
  • NADP--thioredoxin reductase.
  • NADPH:oxidized thioredoxin oxidoreductase.
  • NADPH--thioredoxin reductase.
  • Thioredoxin reductase (NADPH).

Catalytic Activity

[thioredoxin]-dithiol + NADP(+) = [thioredoxin]-disulfide + H(+) + NADPH

Cofactors

There are no Cofactors for this Enzyme

Reaction Mechanism

    Thioredoxin reductase By Reference

    Thioredoxin reductase contains FAD and NADPH binding domains that are structurally similar to the corresponding domains of the related enzyme glutathione reductase. The relative orientation of these domains is, however, very different in the two enzymes: when the FAD domains of thioredoxin and glutathione reductases are superimposed, the NADPH domain of one is rotated by 66 degrees with respect to the other. The observed binding mode of NADP+ in thioredoxin reductase is non-productive in that the nicotinamide ring is more than 17 A from the flavin ring system. Thioredoxin reductase belongs to the class-II pyridine nucleotide-disulfide oxidoreductase family.

    The most direct pathway for reducing equivalents in turnover would require a ternary complex in which the flavin is reduced by NADPH while thioredoxin is being reduced by the active site dithiol when the enzyme is in the proposed FR conformation (allows flavin reduction by pyridine nucleotide). Following the reversal of rotation, the nascent active site disulfide could be reduced by the newly reduced flavin.
    Catalytic Residues
    AA Uniprot Uniprot Resid PDB PDB Resid
    Cys P0A9P4 136 1tde 135
    Cys P0A9P4 139 1tde 138
    Asp P0A9P4 140 1tde 139

Reaction Parameters

There are no kinetic parameters information for this Enzyme

Associated Proteins

Protein name Organism
Thioredoxin reductase-like selenoprotein T1b Zebrafish
Thioredoxin reductase-like selenoprotein T Human
Thioredoxin reductase 1, mitochondrial Mouse-ear cress
Thioredoxin reductase 1, cytoplasmic Human
Thioredoxin reductase SEP1 Emiliania huxleyi

Citations