In enzymology, a d-galactose 1-dehydrogenase (EC 1.1.1.48) is an enzyme that catalyzes the chemical reaction

d-galactose + NAD⁺ ${\displaystyle \rightleftharpoons }$ d-galactono-1,4-lactone + NADH + H⁺

Thus, the two substrates of this enzyme are d-galactose and NAD⁺, whereas its 3 products are d-galactono-1,4-lactone, NADH, and H⁺.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD⁺ or NADP⁺ as acceptor. The systematic name of this enzyme class is d-galactose:NAD⁺ 1-oxidoreductase. Other names in common use include d-galactose dehydrogenase, beta-galactose dehydrogenase, and NAD⁺-dependent d-galactose dehydrogenase. This enzyme participates in galactose metabolism.

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