Thioredoxin reductase two modes of catalysis have evolved.

@article{Williams2000ThioredoxinRT,
  title={Thioredoxin reductase two modes of catalysis have evolved.},
  author={C. Howard Williams and L. David Arscott and Sylke Müller and Brett W. Lennon and Martha Ludwig and P. F. Wang and Donna M. Veine and Katja Becker and R. Heiner Schirmer},
  journal={European journal of biochemistry},
  year={2000},
  volume={267 20},
  pages={
          6110-7
        }
}
Thioredoxin reductase (EC 1.6.4.5) is a widely distributed flavoprotein that catalyzes the NADPH-dependent reduction of thioredoxin. Thioredoxin plays several key roles in maintaining the redox environment of the cell. Like all members of the enzyme family that includes lipoamide dehydrogenase, glutathione reductase and mercuric reductase, thioredoxin reductase contains a redox active disulfide adjacent to the flavin ring. Evolution has produced two forms of thioredoxin reductase, a protein in… 

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