Development of Enzyme-Linked Immunosorbent Assays for Diagnosis of Liver Diseases

尿素循环由氨甲酰磷酸合成酶（CPS）、鸟氨酸转氨甲酰酶（OTC）、氨基琥珀酸合成酶（AS）、氨基琥珀酸裂解酶（AL）和氨基甲酸酯酶五种酶组成。所有这些酶在肝脏中表达最强烈。除肝脏外，CPS和OTC在小肠中中度表达，AS和AL在肾脏中中度表达。在这5种酶中，CPS和OTC是线粒体酶，而AS、AL和ATP酶是胞浆酶。CPS占肝脏总蛋白的4-5%，其他酶占0.1- 0.2%。本文建立了一种灵敏的土霉素酶联免疫吸附试验（ELISA），并证明该方法可用于多种肝病的诊断。除了先前制备的针对OTC和CPS的抗体之外，我们还制备了针对AS、AL和抗凝血酶的抗体。使用这些抗体，我们分析了这些酶的肝内定位。在这五种酶中，CPS、AS、AL和乙酰胆碱酯酶表现出较强的从门周到中心周的带状分布，而OTC仅表现出很弱的带状分布。这些信息对于解释患者血浆中尿素循环酶的ELISA数据将是重要的。

Urea cycle is composed of five enzymes, carbamylphosphate synthetase (CPS), ornithine transcarbamylase (OTC), argininosuccinate synthetase (AS), argininosuccinate lyase (AL) and arginase. All these enzymes are expressed most strongly in the liver. In addition to the liver, CPS and OTC are expressed moderately in the small intestine, and AS and AL are expressed moderately in the kidney. Among the five enzymes, CPS and OTC are mitochondrial, whereas AS,AL and arginase are cytosoloc . CPS consists 4-5% of total liver protein and other enzymes do 0.1-0.2%. We developed a sensitive enzyme-linked immunosorbent assay (ELISA) of OTC and showed that this system will and in diagnosing various liver diseases. In addition to previously prepared antibodies against OTC and CPS,we prepared antibodies against AS,AL and arginase. Using these antibodies, we analyzed intrahepatic localization of these enzymes. Among the five enzymes, CPS,AS,AL and arginase showed a strong peritortal to pericentral zonation, whereas OTC showed only a very weak zonation. These imformations will be important for interpretation of the ELISA data for the urea cycle enzymes in the plasma of patients.