This model represents a subfamily of pfam00107 as defined by Pfam, a superfamily in which some members are zinc-binding medium-chain alcohol dehydrogenases while others are quinone oxidoreductases with no bound zinc. This subfamily includes proteins studied crystallographically for insight into function: YhdH from Escherichia coli and YhfP from Bacillus subtilis. Members bind NADPH or NAD, but not zinc. [Unknown function, Enzymes of unknown specificity]