Versatile oxidoreductase that catalyzes the oxidation and reduction of a broad range of substrates. Preferentially oxidizes secondary alcohols. Has highest activity for racemic 2-octanol. Is also an efficient reductase for selected substrates. Substrate selectivity was found for medium chain lipophilic ketones. Has highest activities for 2-octanone, 2-nonanone and 2-decanone. The enzyme is (S)-selective in the reduction direction and produces exclusively the (S)-enantiomer. a secondary alcohol + NAD(+) = a ketone + H(+) + NADH Binds 2 Zn(2+) ions per subunit. kcat is 1.05 sec(-1) with (S)-2-octanol as substrate and 3.42 sec(-1) for NAD(+). kcat is 0.56 sec(-1) for (2)-octanone. Optimum pH is 9.5 for the oxidation reaction, and 6.5 for the reduction reaction. Optimum temperature is 28-33 degrees Celsius. Active from 22 to 37 degrees Celsius. Homotetramer. Belongs to the zinc-containing alcohol dehydrogenase family.