5'-nucleotide (1 mM), NADH (0.4 mM), glucose 6-phosphate (5.0 mM), glucose &phosphate dehydrogenase (0.6 unit/mL), and 0.25 mL of microsomal suspension in a total volume of 1.25 mL. After 1 h at 37 OC, the incubates were transferred to Amicon Centriflo CF 25 membrane cones (Amicon Corp., Lexington, MA) and centrifuged at 2000 rpm (< 1000g) in a swinging-bucket centrifuge for 75 min at 4" C. The filtrates were analyzed by HPLC on a p- ...