Enzyme reactions for CD spectroscopy were conducted for 5 h at 30 °C in water with 0.4 mm 8-oxogeranial and 1 mm NADPH as substrates and 0.5 μm enzyme. Enzyme was diluted at least 150-fold from a buffered solution. Products were extracted with ethyl acetate. The extract from a 1.6-ml reaction was evaporated and taken up in 200 μl of hexane. Completeness of the reaction was verified by GC-MS. Spectra were recorded in 1-nm steps with 0.5-s averaging time on a Chirascan Plus spectropolarimeter (Applied Photophysics) at 20 °C in a 1-mm cuvette. Three measurements were averaged, and background with only hexane was subtracted.