Table 3. N-Acetylation of arylamines and arylalklylamines by NAT1 and NAT2.

Table values represent the mean ± S.E.M. (n = 3). Controls included no enzyme, no substrate and no acetyl coenzyme A each of which yielded no production of product. All assays were run at 300 µM substrate and 1 mM acetyl coenzyme A at conditions linear with respect to time and enzyme concentration. Differences were tested for significance by Student t test (unpaired). Additional experimental details appear in the Materials and Methods section.

		Substrate
		N-Acetylated product formation (nmol/min/mg protein)
Recombinant human gene	Acetylator phenotype	Sulfamethazine	p-Amino-benzoic acid	Tryptamine	Serotonin
NAT1*4	High	NDc	11,500 ± 1400	0.412 ± 0.038	0.115 ± 0.064
NAT1*14Ba	Low	ND	2,170 ± 159	0.0753±0.0341	0.0361 ± 0.018
NAT2*4	Rapid	545 ± 74	ND	1.98 ± 0.25	0.484 ± 0.045
NAT2*5Bb	Slow	84.5 ± 15.2	ND	0.412±0.079	0.0741± 0.0492

^aRates catalyzed by NAT1*14B were significantly (p<0.005) lower than catalyzed by NAT1*4 towards the N-acetylation of p-aminobenzoic acid and tryptamine.

^bRates catalyzed by NAT2*5B were significantly (p<0.005) lower than catalyzed by NAT2*4 towards the N-acetylation of sulfamethazine, tryptamine, and serotonin.

^cND; Not determined