Department of Chemistry-Biology, University of Québec at Trois-Rivières, C. P. 500, Trois-Rivières, Québec G9A 5H7, Canada.
J Phys Chem B. 2013 May 30;117(21):6403-9. doi: 10.1021/jp402573v. Epub 2013 May 16.
Naturally occurring polymers, such as chitosan, have been extensively studied as carriers for therapeutic protein and gene delivery systems. β-Lactoglobulin (β-LG) is a member of the lipocalin superfamily of transporters for small hydrophobic molecules. We examine the binding of milk β-lactoglobulin with chitosan of different sizes such as chitosan 15, 100, and 200 KD in aqueous solution at pH 5-6, using FTIR, CD, and fluorescence spectroscopic methods. Structural analysis showed that chitosan binds β-LG via both hydrophilic and hydrophobic contacts with overall binding constants of K(β-LG-ch-15) = 4.1 (±0.4) × 10(2) M(-1), K(β-LG-ch-100) = 7.2 (±0.6) × 10(4) M(-1), and K(β-LG-ch-200) = 3.9 (±0.5) × 10(3) M(-1) with the number of bound protein per chitosan (n) 0.9 for ch-15, 0.6 for ch-100, and 1.6 for ch-200. Chitosan 100 KD forms stronger complexes with β-LG than chitosans 200 and 15 KD. Polymer binding did not alter protein conformation inducing structural stabilization. Chitosan 100 is a stronger protein transporter than chitosan 15 and 200 KD.
天然存在的聚合物，如壳聚糖，已被广泛研究作为治疗蛋白和基因传递系统的载体。β-乳球蛋白（β-LG）是一种小分子疏水性分子转运的亲脂性球蛋白超家族的成员。我们在 pH 值为 5-6 的水溶液中，使用傅里叶变换红外光谱（FTIR）、圆二色性（CD）和荧光光谱法，研究了不同大小的壳聚糖（如壳聚糖 15、100 和 200 KD）与乳球蛋白的结合情况。结构分析表明，壳聚糖通过亲水和疏水接触与β-LG 结合，总结合常数为 K（β-LG-ch-15）=4.1（±0.4）×10（2）M（-1），K（β-LG-ch-100）=7.2（±0.6）×10（4）M（-1），K（β-LG-ch-200）=3.9（±0.5）×10（3）M（-1），与每个壳聚糖结合的蛋白数（n）分别为 0.9（ch-15）、0.6（ch-100）和 1.6（ch-200）。壳聚糖 100 KD 与β-LG 形成的复合物比壳聚糖 200 KD 和 15 KD 更强。聚合物结合没有改变蛋白质构象，诱导结构稳定。壳聚糖 100 比壳聚糖 15 和 200 KD 更能有效地转运蛋白。
