Versatile oxidoreductase that catalyzes the oxidation and reduction of polar as well as non-polar substrates at a very broad pH range. Preferentially oxidizes secondary alcohols. Has highest activity for racemic 2-heptanol and racemic octanol. Is also an efficient reductase for selected substrates. Substrate selectivity was found for medium chain length ketones with the carbonyl function at position C-2. Has highest activities for ribulose and fructose. The enzyme is (R)-selective in the reduction direction and produces exclusively the (R)-enantiomer. D-mannitol + NADP(+) = D-fructose + H(+) + NADPH kcat is 3.17 sec(-1) with rac-2-heptanol as substrate and 6.15 sec(-1) for NADP(+). kcat is 5.42 sec(-1) for ribulose. Optimum pH is 10 for the oxidation reaction, and 4-9 for the reduction reaction. Optimum temperature is 25-28 degrees Celsius. Homotetramer. Belongs to the short-chain dehydrogenases/reductases (SDR) family.