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

尿素循环由氨基甲酰磷酸合成酶(CPS)、鸟氨酸转氨甲基酶(OTC)、精氨酸琥珀酸合成酶(AS)、精氨酸琥珀酸裂解酶(AL)和精氨酸酶5种酶组成。所有这些酶在肝脏中的表达最强。除肝脏外，CPS和OTC在小肠中适度表达，AS和AL在肾脏中适度表达。在这五种酶中，CPS和OTC是线粒体，而AS、AL和精氨酸酶是胞质。CPS占总肝脏蛋白的4%-5%，其他酶占0.1%-0.2%。我们建立了一种灵敏的OTC的酶联免疫吸附试验(ELISA)，并表明该系统将用于各种肝病的诊断。除了先前制备的OTC和CPS抗体外，我们还制备了AS、AL和精氨酸酶的抗体。使用这些抗体，我们分析了这些酶在肝脏内的定位。在五种酶中，CPS、AS、AL和精氨酸酶表现出较强的向中心周围的带状，而OTC仅表现出很弱的带状。这些信息将对解释患者血浆中尿素循环酶的酶联免疫吸附试验数据很重要。

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.