Ramkumar R, Podder S K
Department of Biochemistry, Indian Institute of Science, Bangalore, India.
J Mol Recognit. 2000 Sep-Oct;13(5):299-309. doi: 10.1002/1099-1352(200009/10)13:5<299::AID-JMR504>3.0.CO;2-O.
The binding of a 14 kDa beta-galactoside animal lectin to splenocytes has been studied in detail. The binding data show that there are two classes of binding sites on the cells for the lectin: a high-affinity site with a K(a) ranging from 1.1 x 10(6) to 5.1 x 10(5) M (-1) and a low affinity binding site with a K(a) ranging from 7.7 x 10(4) to 3.4 x 10(4) M (-1). The number of receptors per cell for the high- and low-affinity sites is 9 +/- 3 x 10(6) and 2.5 +/- 0.5 x 10(6), respectively. The temperature dependence of the K value yielded the thermodynamic parameters. The energetics of this interaction shows that, although this interaction is essentially enthalpically driven (DeltaH - 21 kJ lambdamol(-1)) for the high-affinity sites, there is a very favorable entropy contribution to the free energy of this interaction (-TDeltaS - 17.5 Jmol(-1)), suggesting that hydrophobic interaction may also be playing a role in this interaction. Lactose brought about a 20% inhibition of this interaction, whereas the glycoprotein asialofetuin brought about a 75% inhibition, suggesting that complex carbohydrate structures are involved in the binding of galectin-1 to splenocytes. Galectin-1 also mediated the binding and adhesion of splenocytes to the extracellular matrix glycoprotein laminin, suggesting a role for it in cell-matrix interactions.
对一种14 kDa的β-半乳糖苷动物凝集素与脾细胞的结合进行了详细研究。结合数据表明，细胞上存在两类该凝集素的结合位点：一类高亲和力位点，其解离常数（K(a)）范围为1.1×10(6)至5.1×10(5) M(-1)；另一类低亲和力结合位点，其K(a)范围为7.7×10(4)至3.4×10(4) M(-1)。高亲和力和低亲和力位点的每个细胞受体数量分别为9±3×10(6)和2.5±0.5×10(6)。K值的温度依赖性产生了热力学参数。这种相互作用的能量学表明，尽管对于高亲和力位点这种相互作用本质上是由焓驱动的（ΔH - 21 kJ·mol(-1)），但对这种相互作用的自由能有非常有利的熵贡献（-TΔS - 17.5 J·mol(-1)），这表明疏水相互作用可能也在这种相互作用中起作用。乳糖对这种相互作用产生20%的抑制，而糖蛋白去唾液酸胎球蛋白产生75%的抑制，这表明复杂碳水化合物结构参与了半乳糖凝集素-1与脾细胞的结合。半乳糖凝集素-1还介导了脾细胞与细胞外基质糖蛋白层粘连蛋白的结合和黏附，表明其在细胞-基质相互作用中发挥作用。
