FIG. 5.

The NADPH-dependent acetoin reductase reaction catalyzed by purified Ara1p-6His analyzed by gas chromatography. (A) Profile of reaction products obtained from Ara1p-6his. Ara1p-6His (0.07 U measured as NADPH-dependent acetoin reductase activity at 50 mM acetoin and 0.2 mM NADPH) was incubated for 24 h with 50 mM (R/S)-acetoin, 1 mM NADPH, 50 mM glucose-6-phosphate, and 10 U of glucose-6-phosphate dehydrogenase. The reaction mixture, together with 1-hexanol as an internal standard, was extracted with chloroform as described previously (13). (B) Profile of reaction products obtained in the control reaction. The reaction mixture contained the same reagents as in panel A, except for Ara1p-6His.