Beckmann J D, Spurzem J R, Rennard S I
Department of Internal Medicine Pulmonary and Critical Care, University of Nebraska Medical Center, Omaha 68198.
Cell Tissue Res. 1993 Dec;274(3):475-85. doi: 10.1007/BF00314544.
Phenol (aryl) sulfotransferases (PSTs) provide a conjugative pathway that detoxifies hydroxylated aromatic xenobiotics by esterification with sulfate. Both human and bovine airways have been reported to use this pathway, and in this investigation the bovine system is examined. PST activity in tracheal through fourth generation bronchial mucosal cytosols was 0.1-0.35 nmol/mg protein/min. Activity was generally greater in more distal bronchi and in parenchymal extracts, which contained 0.6-3 nmol/mg/min PST activity. Comparison of the PST activities of bronchial and parenchymal cytosols indicated similar pH activity profiles, although steady state kinetic measurements revealed different Km values for the acceptor substrate 2-naphthol (13.7 microM for bronchial, 31.3 microM for parenchymal). Anion exchange chromatography indicated two PST isoforms being expressed in different ratios. Immunoblot analysis with mouse anti-bovine PST revealed a closely spaced doublet at 32 kDa in both bronchial mucosal and parenchymal cytosolic extracts; however, this doublet was unequally stained in parenchymal extracts. Immunohistochemical analyses revealed faint positive staining of the tracheobronchial epithelium. Greatest immunostaining was observed in the nonciliated secretory epithelial cells of the bronchioles, whereas surrounding smooth muscle, endothelial cells, and alveoli were immunonegative. These results are consistent with the known locations of other detoxification enzymes within the airways.
苯酚（芳基）磺基转移酶（PSTs）提供了一条结合途径，通过与硫酸盐酯化作用使羟基化芳香族外源性物质解毒。据报道，人类和牛的气道都使用这条途径，在本研究中对牛的系统进行了检测。气管至第四代支气管黏膜胞质溶胶中的PST活性为0.1 - 0.35纳摩尔/毫克蛋白质/分钟。在更远端的支气管和实质提取物中活性通常更高，实质提取物中PST活性为0.6 - 3纳摩尔/毫克/分钟。支气管和实质胞质溶胶的PST活性比较表明，尽管稳态动力学测量显示受体底物2 - 萘酚的Km值不同（支气管为13.7微摩尔，实质为31.3微摩尔），但其pH活性曲线相似。阴离子交换色谱表明两种PST同工型以不同比例表达。用小鼠抗牛PST进行免疫印迹分析显示，在支气管黏膜和实质胞质提取物中均有一条紧密间隔的32 kDa双峰；然而，该双峰在实质提取物中的染色不均等。免疫组织化学分析显示气管支气管上皮呈弱阳性染色。在细支气管的无纤毛分泌上皮细胞中观察到最强的免疫染色，而周围的平滑肌、内皮细胞和肺泡均为免疫阴性。这些结果与气道内其他解毒酶的已知位置一致。
