TABLE 3.

Kinetic constants for recombinantly expressed S. cerevisiae ALDHs^a

Enzyme	Propionaldehyde-NADPb			Acetaldehyde-NADPc			Propionaldehyde-NADd
	Km		Vmax	Km		Vmax	Km		Vmax
	NADP	Aldehyde		NADP	Aldehyde		NAD	Aldehyde
ALDH1	99	30	14	40	24	24	17,400	700	8.3
ALDH5	3,470	390	0.45	640	58	1.1	6,430	830	0.011
ALDH2e	447	17	2.1	1,400	10	5.2	1,100	13	4.2

^aThe unit for K_m was μM, and V_max was presented as μmol/min/mg of protein. The assays were performed in 100 mM sodium phosphate, pH 7.4. 

^bThe K_ms for NADP of cytosolic ALDH1, mitochondrial ALDH5, and commercial ALDH2 were obtained with 0.7, 5.6, and 0.28 mM propionaldehyde, respectively. The K_m values for propionaldehyde were determined with 2, 20, and 15 mM NADP. 

^cThe K_ms for NADP of ALDH1, ALDH5, and ALDH2 were obtained with 0.9, 1.2, and 0.18 mM acetaldehyde, respectively. The K_m values for acetaldehyde were determined with 2, 10, and 15 mM NADP. 

^dThe K_ms for NAD of ALDH1, ALDH5, and ALDH2 were obtained with 7, 5.6, and 0.28 mM propionaldehyde, respectively. The K_m values for propionaldehyde were determined with 20 mM NAD. The standard deviation was less than ±15%. 

^eThe commercial yeast ALDH2 was estimated to be about 60% pure.