TABLE 1.

Acetaldehyde dehydrogenase activity in soluble protein fractions from the ZM4 and ΔaldB strains^a

Strain	Cofactor	Activityb	Relative activity (%)b
ZM4 WT	NADP+	0.18 ± 0.04	1.00
ΔaldB mutant	NADP+	N.D.c	N.D.
ZM4 WT	NAD+	0.04 ± 0.01	0.24
ΔaldB mutant	NAD+	0.03 ± 0.00	0.17

^aSoluble protein fraction (FI) was obtained as described in Materials and Methods. Each enzymatic reaction of 1 mL contained 0.1 M Tris HCl pH 8.0, 0.1 M KCl, 10 mM β-mercaptoethanol, 2 mM acetaldehyde, and 0.67 mM NAD⁺ or NADP⁺ (protocol for yeast acetaldehyde dehydrogenase from Sigma-Aldrich). Reaction was started by adding 33 μl of FI and measured for 30 min at 25°C in 24-well microtiter plate using plate reader. Absorbance at 340 nm in control without FI was subtracted from the reactions.

^bActivity was calculated as increase in NAD(P)H concentration/min/mL per milligram of total protein in FI. Millimolar extinction coefficient for NAD(P)H in 1 mL of solution in 24-well plate was determined experimentally as 4.35. Values represent the average and standard deviation from three independent experiments with three technical repeats.

^cN.D., not detected.