Minchin R F
Department of Pharmacology, University of Western Australia, Nedlands.
Biochem J. 1995 Apr 1;307 ( Pt 1)(Pt 1):1-3. doi: 10.1042/bj3070001.
N-acetyl-p-aminobenzoylglutamate is a major urinary metabolite of folic acid. It is formed by acetylation of p-aminobenzoylglutamate following cleavage of the C9-N10 bond of folic acid. Using recombinant human type 1 (NAT1) and type 2 (NAT2) arylamine N-acetyltransferase, we have shown that p-aminobenzoylglutamate is a specific NAT1 substrate. At an acetyl-CoA concentration of 50 microM, the Km for p-aminobenzoylglutamate (pABG) acetylation by recombinant NAT1 was 130 +/- 13 microM. For the human pro-monocytic cell-line U937, the apparent Km was slightly higher (333 +/- 17 microM). Inhibitor studies supported NAT1-dependent acetylation of pABG by U937 cell cytosols. These studies are the first to identify a potential endogenous substrate for human NAT1 and suggest that this enzyme may be important in the cellular clearance of pABG.
N-乙酰对氨基苯甲酰谷氨酸是叶酸的一种主要尿液代谢产物。它是在叶酸的C9-N10键断裂后，由对氨基苯甲酰谷氨酸乙酰化形成的。使用重组人1型（NAT1）和2型（NAT2）芳胺N-乙酰基转移酶，我们已经证明对氨基苯甲酰谷氨酸是一种特异性的NAT1底物。在乙酰辅酶A浓度为50微摩尔时，重组NAT1对氨基苯甲酰谷氨酸（pABG）乙酰化的Km值为130±13微摩尔。对于人原单核细胞系U937，表观Km值略高（333±17微摩尔）。抑制剂研究支持U937细胞胞质溶胶对pABG的NAT1依赖性乙酰化。这些研究首次确定了人NAT1的一种潜在内源性底物，并表明该酶可能在pABG的细胞清除中起重要作用。
