Roguin L P, Delfino J M, Vita N, Paladini A C
Biochem J. 1984 Dec 1;224(2):535-40. doi: 10.1042/bj2240535.
Bovine somatotropin with an increasing number of its carboxylate groups modified by reaction with glycine methyl ester in the presence of a water-soluble carbodi-imide was tested for its activity in different bioassays. Only those derivatives which were known to be active in the body-weight-increase bioassay were able to compete with 125I-labelled bovine somatotropin for their specific binding sites in vivo. No difference was found in the rate of clearance of a poorly active derivative as compared with that of native somatotropin. In contrast, both active and inactive derivatives were found to be equally effective in displacing the tracer from its binding sites present in isolated cells and membrane preparations from rat liver. These results suggest that the liver somatogenic receptors studied in vitro are less discriminating than those detected in vivo.
用甘氨酸甲酯在水溶性碳二亚胺存在下与牛生长激素反应，使其羧基数量增加的牛生长激素衍生物，在不同生物测定中测试其活性。只有那些已知在体重增加生物测定中有活性的衍生物，才能在体内与125I标记的牛生长激素竞争其特异性结合位点。与天然生长激素相比，活性较差的衍生物的清除率没有差异。相反，发现活性和非活性衍生物在从大鼠肝脏分离的细胞和膜制剂中存在的结合位点上取代示踪剂方面同样有效。这些结果表明，体外研究的肝脏生长激素受体比体内检测到的受体区分能力更弱。
