碳水化合物在促甲状腺激素结合位点中的作用。

Role of carbohydrates in thyrotropin binding sites.

作者信息

Pekonen F

出版信息

Horm Metab Res. 1980 Jul;12(7):310-4. doi: 10.1055/s-2007-996277.

DOI:10.1055/s-2007-996277

Abstract

The role of carbohydrates in thyrotropin binding was studied by glycosidase treatment of human thyroid membranes. Removal of over 75% of membrane sialic acid resulted in a 50% increase of TSH binding, measured in 10 mM Tris-HCl, 50 mM NaCl, 0.1% bSA, pH 7.4, 37 degrees C (buffer A). This augmentation was due to an increase in binding to high affinity sites (Ka 1 X 10(10)M-1). The binding was highly specific and was not significantly inhibited by gangliosides. In contrast, low affinity binding of TSH was unchanged either in buffer A or in 10 mM Tris-acetate, 0.1% bSA pH 6.0, 4 degrees C (buffer B) and was inhibited by gangliosides. Treatment of membranes with beta-galactosidase, beta-N-acetylglucosaminidase and alpha-L-fucosidase had little effect on TSH binding. The data suggests that membrane-associated sialic acid inhibits TSH binding to high affinity receptors and that gangliosides are not involved in tthis TSH-receptor interaction.

摘要

通过对人甲状腺膜进行糖苷酶处理，研究了碳水化合物在促甲状腺激素结合中的作用。在10 mM Tris-HCl、50 mM NaCl、0.1%牛血清白蛋白、pH 7.4、37℃（缓冲液A）条件下测定，去除超过75%的膜唾液酸后，促甲状腺激素（TSH）结合增加了50%。这种增加是由于与高亲和力位点（Ka 1×10¹⁰M⁻¹）的结合增加所致。该结合具有高度特异性，且不受神经节苷脂的显著抑制。相比之下，在缓冲液A或10 mM Tris-乙酸盐、0.1%牛血清白蛋白、pH 6.0、4℃（缓冲液B）中，TSH的低亲和力结合没有变化，且受神经节苷脂抑制。用β-半乳糖苷酶、β-N-乙酰氨基葡萄糖苷酶和α-L-岩藻糖苷酶处理膜对TSH结合影响不大。数据表明，膜相关唾液酸抑制TSH与高亲和力受体的结合，且神经节苷脂不参与这种TSH-受体相互作用。