Guray T, Guvenc T
Department of Biological Sciences, Middle East Technical University, Ankara, Turkey.
Comp Biochem Physiol C Pharmacol Toxicol Endocrinol. 1997 Nov;118(3):305-10. doi: 10.1016/s0742-8413(97)00175-8.
Acetyl coenzyme A-dependent arylamine N-acetyltransferases (NATs), EC 2.3.1.5. were measured in sheep tissues (N = 14) using p-aminobenzoic acid (PABA) as a substrate. Specific activities of liver, kidney, and lung NATs were 5.3 x 10(-3) +/- 1.4 (mean +/- SE) nmoles.min-1.mg protein-1, 3.4 x 10(-3) +/- 1.1 nmoles.min-1.mg protein-1, 2.5 x 10(-3) +/- 1.2 nmoles.min-1.mg protein-1, respectively. Km values were 53 +/- 3 microM for liver, 34 +/- 2 microM for kidney, and 28 +/- 2 microM for lung tissue. Optimum pH for the acetylation reaction was found as 7.5. The enzyme activity was stable for at least 6 months in all tissues, when stored at -70 degrees C. The enzyme from sheep tissues were quite heat-stable. Inhibition studies showed that N-ethylmaleimide was a potent inhibitor of sheep tissue NAT enzymes.
以对氨基苯甲酸（PABA）为底物，测定了14只绵羊组织中依赖乙酰辅酶A的芳胺N - 乙酰基转移酶（NATs，EC 2.3.1.5）的活性。肝脏、肾脏和肺脏NATs的比活性分别为5.3×10⁻³±1.4（平均值±标准误）纳摩尔·分钟⁻¹·毫克蛋白⁻¹、3.4×10⁻³±1.1纳摩尔·分钟⁻¹·毫克蛋白⁻¹、2.5×10⁻³±1.2纳摩尔·分钟⁻¹·毫克蛋白⁻¹。肝脏、肾脏和肺组织的米氏常数（Km）分别为53±3微摩尔、34±2微摩尔和28±2微摩尔。乙酰化反应的最适pH值为7.5。当在-70℃储存时，该酶活性在所有组织中至少6个月保持稳定。绵羊组织中的酶具有相当高的热稳定性。抑制研究表明，N - 乙基马来酰亚胺是绵羊组织NAT酶的有效抑制剂。
