Maruhama Y, Hikichi I, Saito F, Hashimoto T, Kaneko H, Takahashi K, Kaito I
Tohoku J Exp Med. 1983 Oct;141(2):199-205. doi: 10.1620/tjem.141.199.
The important function of sialic acids in glycoproteins is to prolong the half life of the glycoproteins in the circulation. In this study, the sialic acid content of plasma low density lipoprotein (LDL)-apoproteins (predominantly B-100 apoprotein, a sialoglycoprotein) was analyzed together with relative electrophoretic mobility of LDL in 46 hypercholesterolemic and normo-cholesterolemic diabetics and non-diabetics. There was a significant positive correlation between the LDL-sialic acid content and LDL mobility either in the non-diabetics (r = 0.534, p less than 0.01) or in the diabetics (r = 0.482, p less than 0.02). Thus, the effect of the LDL-sialic acids upon the LDL electric charge was apparent. However, the LDL-sialic acids in the hypercholesterolemic diabetics were significantly (p less than 0.01) decreased to 9.64 +/- 0.63 micrograms/mg LDL protein (mean +/- S.E.) as compared with that in the normocholesterolemic diabetics (12.85 +/- 0.62 micrograms/mg LDL protein). Since the relatively sialic acid-poor LDL particles are rather accumulated in plasma of diabetic patients, the grade of sialylation of glycoprotein seems to have no role in the interaction with peripheral cells and therefore, the glycoprotein turnover, as far as the LDL apoproteins are concerned.
唾液酸在糖蛋白中的重要功能是延长糖蛋白在循环中的半衰期。在本研究中，分析了46例高胆固醇血症和正常胆固醇血症的糖尿病患者及非糖尿病患者血浆低密度脂蛋白（LDL）-载脂蛋白（主要是B-100载脂蛋白，一种唾液糖蛋白）的唾液酸含量以及LDL的相对电泳迁移率。在非糖尿病患者（r = 0.534，p < 0.01）或糖尿病患者（r = 0.482，p < 0.02）中，LDL-唾液酸含量与LDL迁移率之间均存在显著正相关。因此，LDL-唾液酸对LDL电荷的影响是明显的。然而，与正常胆固醇血症糖尿病患者（12.85±0.62微克/毫克LDL蛋白）相比，高胆固醇血症糖尿病患者的LDL-唾液酸显著降低（p < 0.01），降至9.64±0.63微克/毫克LDL蛋白（平均值±标准误）。由于相对缺乏唾液酸的LDL颗粒在糖尿病患者血浆中积累较多，就LDL载脂蛋白而言，糖蛋白的唾液酸化程度似乎在与外周细胞的相互作用以及因此在糖蛋白周转中不起作用。
