Effects of vitamin C on arylamine N-acetyltransferase activity in human liver tumor cells.
Arylamine N-acetyltransferase (NAT) activity in a human liver tumor (heptoma) cell line was inhibited by vitamin C. Using high performance liquid chromatography, NAT activity on the acetylation of 2-aminofluorene and p-aminobenzoic acid was examined. Two assay systems were performed, one with cellular cytosols, the other with intact liver tumor cell suspensions. The NAT activity in a human liver tumor cell line was inhibited by vitamin C in a dose-dependent manner in both types of examined system: i.e. the greater the concentration of vitamin C in the reaction, the greater the inhibition of NAT activities in both systems examined. The data also indicated that vitamin C decreased the apparent Km and Vmax of NAT enzymes from human liver tumor cells in both systems examined. This report is the first demonstration which showed vitamin C effect on human liver tumor cell NAT activity.
Wu
L T
LT
Department of Microbiology, China Medical College, Taiwan, Republic of China.
Chung
J G
JG
D010129:4-Aminobenzoic Acid / Q000378:metabolism; D000107:Acetylation; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism*; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D002273:Carcinogens / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005449:Fluorenes / Q000378:metabolism; D006801:Humans; D008113:Liver Neoplasms / Q000201:enzymology*; D009363:Neoplasm Proteins / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000201:enzymology
D002273:Carcinogens; D005449:Fluorenes; D009363:Neoplasm Proteins; C012177:2-aminofluorene; D001191:Arylamine N-Acetyltransferase; D001205:Ascorbic Acid; D010129:4-Aminobenzoic Acid