Sorrentino S, Tucker G K, Glitz D G
Department of Biological Chemistry, UCLA School of Medicine 90024-1737.
J Biol Chem. 1988 Nov 5;263(31):16125-31.
The major ribonuclease of human liver has been isolated in a four-step procedure. The protein appears homogeneous by several criteria. The amino acid composition and the amino-terminal sequence of the enzyme indicate that the protein is related to human pancreatic ribonuclease and to angiogenin, and that it may be identical with an eosinophil-derived neurotoxin and to a ribonuclease that has been isolated from urine. The catalytic activity of the liver ribonuclease and its sensitivity to iodoacetic acid inactivation also relate the enzyme to the pancreatic RNases, but the liver protein is clearly differentiated by immunological measurements. Antibodies to the liver ribonuclease inhibit its activity, but not that of the human pancreatic enzyme; cross-reactivity in a radioimmunological assay is small but measurable. Immunochemical measurements have been used to examine the distribution of the liver-type protein in other tissues. Inhibition of enzyme activity by anti-liver ribonuclease shows that a cross-reactive enzyme is predominant in extracts of spleen and is a significant component in kidney preparations, while the liver-type protein is almost absent in brain or pancreas homogenates. Cross-reactive ribonuclease is present in serum, but levels are not correlated with any of the disease states examined.
人肝脏的主要核糖核酸酶已通过四步程序分离出来。从几个标准来看，该蛋白质显得均一。该酶的氨基酸组成和氨基末端序列表明，该蛋白质与人类胰腺核糖核酸酶和血管生成素有关，并且可能与嗜酸性粒细胞衍生的神经毒素以及从尿液中分离出的一种核糖核酸酶相同。肝脏核糖核酸酶的催化活性及其对碘乙酸失活的敏感性也表明该酶与胰腺核糖核酸酶有关，但通过免疫学测量可清楚地区分肝脏蛋白质。针对肝脏核糖核酸酶的抗体可抑制其活性，但不能抑制人类胰腺酶的活性；放射免疫测定中的交叉反应性较小但可测量。免疫化学测量已用于检查肝脏型蛋白质在其他组织中的分布。抗肝脏核糖核酸酶对酶活性的抑制表明，交叉反应性酶在脾脏提取物中占主导地位，是肾脏制剂中的重要成分，而在脑或胰腺匀浆中几乎不存在肝脏型蛋白质。交叉反应性核糖核酸酶存在于血清中，但水平与所检查的任何疾病状态均无关联。
