Ozawa Y, Chopra I J, Solomon D H, Smith F
Endocrinology. 1979 Nov;105(5):1221-5. doi: 10.1210/endo-105-5-1221.
The effects of sulfhydryl (SH) reagents on the binding of TSH to thyroid membranes and on membrane adenylate cyclase activity were studied. Diamide, a SH-oxidizing agent, enhanced [125I]iodo-TSH binding to thyroid membranes in a dose-dependent manner. On the contrary, dithiothreitol (DTT), a disulfide-reducing reagent, markedly inhibited this activity in a dose-dependent manner. These effects could not be attributed to a direct interaction between the reagents and the radioactive TSH. Scatchard plot analysis of the data was limited by curvilinear plots but suggested that diamide increases while DTT decreases the affinity of the receptors for TSH in thyroid membranes, neither reagent appeared to influence the capacity of TSH binding by membranes. The effects of diamide and DTT on adenylate cyclase activity of thyroid plasma membranes were just the opposite of their effects on TSH binding. Thus, diamide inhibited adenylate cyclase activity of thyroid plasma membranes while DTT increased basal enzyme activity and slightly but not significantly increased TSH-stimulated enzyme activity. The data suggest a possible physiological role for SH and disulfide groups of thyroid membranes in modulation of thyroidal activity.
研究了巯基（SH）试剂对促甲状腺激素（TSH）与甲状腺膜结合以及对膜腺苷酸环化酶活性的影响。二酰胺是一种SH氧化剂，它以剂量依赖的方式增强了[125I]碘-TSH与甲状腺膜的结合。相反，二硫苏糖醇（DTT）是一种二硫键还原剂，它以剂量依赖的方式显著抑制了这种活性。这些作用不能归因于试剂与放射性TSH之间的直接相互作用。对数据的Scatchard作图分析受到曲线的限制，但表明二酰胺增加而DTT降低了甲状腺膜中TSH受体的亲和力，两种试剂似乎都不影响膜结合TSH的能力。二酰胺和DTT对甲状腺质膜腺苷酸环化酶活性的影响与其对TSH结合的影响正好相反。因此，二酰胺抑制甲状腺质膜的腺苷酸环化酶活性，而DTT增加基础酶活性，并轻微但不显著地增加TSH刺激的酶活性。数据表明甲状腺膜的SH和二硫键基团在调节甲状腺活性方面可能具有生理作用。
