Abstract: A hybridomas secreting McAb 1G₁₀ which can inhibit the catalytic activity of carboxypeptidase A (CPA) was prepared and characterized. Analyzing the model of cell nucleus, main chromosome number was between 80-90. The titer of the ascites fluid was 10⁶. Binding constant for McAb 1G₁₀ to CPA was 1.59×10⁹(mol/L)^-1. McAb 1G₁₀ was identified as belonging to the IgG₁ subclass.Its molecular weight was about 150 Kd. The interaction of McAb 1G₁₀ with CPA was investigated. A competitive inhibition of peptidase activity of CPA by McAb 1G₁₀ was shown by Dixon Plot. The apparent inhibitory constant obtained by this procedure was 1.17×10^-7 mol/L. These results suggested that the binding site of McAb 1G₁₀ with CPA may be the active site of CPA for its peptidase activity. Based on this work, the idiotypic antibody which is the “Internal-Image” of CPA can be prepared and may have the similar enzymatic activity with CPA.

Key words: monoclonal antibody, CPA, inhibition of enzymatic activity

摘要： 以羧肽酶A为抗原，经动物免疫、细胞融合、筛选及3次克隆化培养，获得了一株稳定分泌对羧肽酶A肽酶活性有抑制作用的单克隆抗体的杂交瘤细胞株1G₁₀。染色体数目为80-90；ELISA测定腹水效价为10⁶；亲和常数为1.59×10⁹(mol/L)^-1；免疫球蛋白属IgG₁型；分子量为150 Kd。羧肽酶A与该抗体反应后测定肽酶活性，显示出该抗体能抑制羧肽酶A的肽酶活性，Dixon法作图表明类似竞争性抑制反应，测得其表观抑制常数为1.17×10^-7mol/L。该抗体可能针对羧肽酶A的活性中心部位，为制备具有抗原内影像作用的抗独特型抗体酶打下了基础。

关键词: 单克隆抗体, 羧肽酶A, 抑制酶活性