D-sorbitol is an acyclic polyol that is commonly added to media to allow growth of cells with a defective cell wall. Growth on media supplemented with 1M D-sorbitol results in a 35% increase in mean life span (Kaeberlein et al., 2002). Addition of 1M D-sorbitol to the growth media suppresses the short life-span of an mpt5 mutant (Kaeberlein and Guarente, 2002). http://uwaging.org/genesdb/gene.php?id=228 In enzymology, a D-iditol 2-dehydrogenase (EC 18.104.22.168) is an enzyme that catalyzes the chemical reaction D-iditol + NAD+ D-sorbose + NADH + H+ Thus, the two substrates of this enzyme are D-iditol and NAD+, whereas its 3 products are D-sorbose, 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-iditol:NAD+ 2-oxidoreductase. This enzyme is also called D-sorbitol dehydrogenase. This enzyme participates in pentose and glucuronate interconversions and fructose and mannose metabolism.