Hattori M, Ozawa K, Wakabayashi K
Institute of Endocrinology, Gunma University, Maebashi, Japan.
Acta Endocrinol (Copenh). 1988 Jan;117(1):73-9. doi: 10.1530/acta.0.1170073.
The present study was performed to evaluate the different carbohydrate structure of rat LH isoelectric components related to their intrinsic biological activities. Terminal sialic acid residues were essential to the formation of multiple LH components observed in the isoelectric focussing profile, which was proved by their interaction with Ricinus communis agglutinin-120 following neuraminidase treatment, and the conversion of component F (pI, 10.0) to less alkaline components after incubation with liver Golgi membrane fraction in the presence of CMP-NeuNAc. The affinity studies using lentil lectin indicated that component F was not an asialo form of component A (pI 8.4). The serial removal of sialic acid residues from these components led to increases in the steroidogenic activity, owing to increases in the activation of the receptor-adenylate cyclase system. The enhancement of the steroidogenic activity by desialylation was very great in component A'(pI, 8.0) (751% increase), and decreased with increasing pI. It can be concluded that the different biological potencies of intact LH components are attributable principally to terminal sialic acid residues. However, the peripheral chains of asialo oligosaccharides of less alkaline components (pI, 8.0, 8.4) seem to prevent the maximal cellular responses, since their desialylated forms did not attain the maximum activity.
本研究旨在评估大鼠促黄体生成素（LH）等电组分的不同碳水化合物结构与其内在生物活性之间的关系。末端唾液酸残基对于在等电聚焦图谱中观察到的多种LH组分的形成至关重要，这一点通过神经氨酸酶处理后它们与蓖麻凝集素-120的相互作用得以证明，并且在CMP-唾液酸存在的情况下，组分F（pI，10.0）与肝高尔基体膜部分孵育后会转化为碱性较弱的组分。使用扁豆凝集素的亲和性研究表明，组分F不是组分A（pI 8.4）的去唾液酸形式。从这些组分中连续去除唾液酸残基会导致类固醇生成活性增加，这是由于受体 - 腺苷酸环化酶系统的激活增加所致。去唾液酸化对类固醇生成活性的增强在组分A'（pI，8.0）中非常显著（增加了751%），并且随着pI的增加而降低。可以得出结论，完整LH组分的不同生物效能主要归因于末端唾液酸残基。然而，碱性较弱的组分（pI，8.0，8.4）的去唾液酸寡糖的外围链似乎会阻止最大细胞反应，因为它们的去唾液酸形式并未达到最大活性。
