Mycothione reductase () is an enzyme that catalyzes the chemical reaction
in M. tuberculosis and other actinomycetes.
The two substrates of this enzyme are mycothione and reduced nicotinamide adenine dinucleotide phosphate (NADPH). The products are two molecules of mycothiol and one of NADP<sup>+</sup>.
This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is mycothiol:NAD(P)+ oxidoreductase. This enzyme is also called mycothiol-disulfide reductase.