Identification and characterization of two isozymic forms of arylamine N-acetyltransferase in Syrian hamster skin.
Arylamine N-acetyltransferase (EC 2.3.1.5) activity was examined using skin from Syrian hamster. Two isozymes of arylamine N-acetyltransferase, designated NAT-1 and NAT-2, were detected on anion-exchange high-performance liquid chromatography analysis. Both enzyme activities had indistinguishable molecular masses (30 kDa), but differed significantly in their specificity toward the aromatic amines including serotonin, dopamine, methoxytryptamine, tryptamine, para-phenetidine, para-aminobenzoic acid, and sulphamethazine. Specifically, NAT-2 but not NAT-1 catalyzed acetylation of dopamine to N-acetyldopamine and acetylation of serotonin to form N-acetylserotonin, a direct precursor of melatonin. The two isozymes were also distinguishable based upon their sensitivity toward methotrexate inhibition (50% inhibiting dose for NAT-1 = 380 microM; NAT-2 > 2 mM). The presence of these two activities in the skin raises new questions about the physiologic role of this enzyme in general and in the skin-specific functions in particular.
Gaudet
S J
SJ
Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892.
Slominski
A
A
Etminan
M
M
Pruski
D
D
Paus
R
R
Namboodiri
M A
MA
D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000032:analysis* / Q000037:antagonists & inhibitors; D002851:Chromatography, High Pressure Liquid; D006224:Cricetinae; D007527:Isoenzymes / Q000032:analysis* / Q000378:metabolism; D008297:Male; D008647:Mesocricetus; D008727:Methotrexate / Q000494:pharmacology; D012867:Skin / Q000201:enzymology* / Q000378:metabolism; D013379:Substrate Specificity
D007527:Isoenzymes; D001191:Arylamine N-Acetyltransferase; D008727:Methotrexate