Evidence for arylamine N-acetyltransferase activity in the fungi Candida albicans.
N-acetyltransferase activities were determined in Candida albicans, which is a member of the normal flora of the mucous membranes in the respiratory, gastrointestinal and female genital tract. The N-acetylation of 2-aminofluorene and p-aminobenzoic acid by the N-acetyltransferase from Candida albicans was determined using high pressure liquid chromatography. The activities (mean +/- S.D.) of N-acetyltransferase from Candida albicans cytosols were 1.06 +/- 0.01 nmol/min per mg protein for the acetylation of 2-aminofluorene substrate, and not detectable levels of acetyl-p-aminobenzoic acid for the acetylation of p-aminobenzoic acid. The apparent kinetic constants Km and Vmax values were 0.17 +/- 0.06 mM and 1.43 +/- 0.42 nmol/min per mg protein, respectively, for 2-aminofluorene substrate. The optimum pH value for the enzyme activity was 8.0. The optimal temperature for the enzyme activity is 40 degrees C for 2-aminofluorene substrate. Among a series of divalent cations and salts, Fe2+, SCN-, I-, and NH4+ were demonstrated to be the most potent inhibitors. The N-acetyltransferase activity was inhibited by iodoacetamide: at 0.25 mM iodoacetamide, activity was reduced 50% and 1.0 mM iodoacetamide inhibited activity more than 90%. This is the first demonstration of acetyl CoA arylamine N-acetyltransferase activity in the yeast-like fungus Candida albicans.
Fang
S H
SH
Department of Medicine, China Medical College, Taichung, Taiwan, ROC.
Chung
J G
JG
Chang
W C
WC
Chang
S S
SS
D010129:4-Aminobenzoic Acid / Q000378:metabolism; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism*; D002176:Candida albicans / Q000201:enzymology*; D002851:Chromatography, High Pressure Liquid; D003600:Cytosol / Q000201:enzymology; D005449:Fluorenes / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D013696:Temperature
D005449:Fluorenes; C012177:2-aminofluorene; D001191:Arylamine N-Acetyltransferase; D010129:4-Aminobenzoic Acid