Enzymatic reactions were conducted as described in the Materials and methods with GS-trans-2-hexanal and GS-trans-2, 4-hexadienal at 0.2 µM. A) HPLC-UV analysis. Reaction mixtures (100 µl) were loaded onto HPLC and separated as described in the Materials and methods. Images show the products GS-trans-2-hexanol and GS-trans-2, 4-hexadienol (labeled). The peak at about 10 min is β-mercaptoethanol present in the AKR1B10 protein preparation. (B) Full scan mass spectra (m/z 150–600), performed as described in the Materials and Methods. GS-trans-2-hexanol and GS-trans-2, 4-hexadienol have [M+H]+ 408.1 and 406.1, respectively.