Differences between murine arylamine N-acetyltransferase type 1 and human arylamine N-acetyltransferase type 2 defined by substrate specificity and inhibitor binding

Table 2 Effects of naphthoquinone 1 on the activity of mammalian NATs and their colorimetric detection

Enzyme		(HUMAN) NAT1*4	(MOUSE) NAT2*1	(MESAU) NAT2*1	(MOUSE) NAT2_F125S	(MOUSE) NAT2_R127G	(MOUSE) NAT2_R127L	(MOUSE) NAT1*1	(HUMAN) NAT2*4
Primary sequence identity versus (HUMAN)NAT1*4		100	82	81	82	82	82	74	71
Active site residues	125	F	F	F	S	F	F	Y	S
	127	R	R	R	R	G	L	G	S
	129	Y	Y	L	Y	Y	Y	Y	S
IC₅₀ with naphthoquinone 1 (μ M)		5.3^a	1.3^a,b	89.0^c	68.7	51.7^a	102.5^a	129.7	>100
λ _max of naphthoquinone 1 (nm)		585^a,b	625^a,b	525^c	498	498^a	498^a	498^b	498^a

IC₅₀ values were calculated using decreasing concentrations of naphthoquinone 1. NAT activity was measured following the hydrolysis rate of AcCoA (400 μM) in the presence of 4ABA for (HUMAN)NAT1*4, (MOUSE)NAT2*1 and (MESAU)NAT2*1; 5AS for (MOUSE)NAT2 mutants and (MOUSE)NAT1*1; and 2-aminofluorene for (HUMAN)NAT2*4. ^aadapted from [25]^badapted from [24]^cadapted from [26]. Residues which are different from the corresponding residues in (HUMAN)NAT1*4 are labeled in bold.

ISSN: 2050-6511