Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025, India.
Appl Biochem Biotechnol. 2019 Aug;188(4):927-941. doi: 10.1007/s12010-019-02972-9. Epub 2019 Feb 9.
The folding and unfolding of proteins inside a cell take place in the presence of macromolecules of various shapes and sizes. Such crowded conditions can significantly affect folding, stability, and biophysical properties of proteins. Thus, to logically mimic the intracellular environment, the thermodynamic stability of two different proteins (lysozyme and α-lactalbumin) was investigated in the presence of mixtures of three crowding agents (ficoll 70, dextran 70, and dextran 40) at different pH values. These crowders possess different shapes and sizes. It was observed that the stabilizing effect of mixtures of crowders is more than the sum effects of the individual crowder, i.e., the stabilizing effect is non-additive in nature. Moreover, dextran 40 (in the mixture) has been found to exhibit the greatest stabilization when compared with other crowders in the mixture. In other words, the small size of the crowder has been observed to be a dominant factor in stabilization of the proteins. Graphical Abstract.
蛋白质在细胞内的折叠和展开是在各种形状和大小的大分子存在的情况下发生的。这种拥挤的条件会显著影响蛋白质的折叠、稳定性和生物物理特性。因此，为了逻辑地模拟细胞内环境，在不同 pH 值下，研究了两种不同蛋白质（溶菌酶和α-乳白蛋白）在三种拥挤剂（菲可、葡聚糖 70 和葡聚糖 40）混合物存在下的热力学稳定性。这些拥挤剂具有不同的形状和大小。结果表明，拥挤剂混合物的稳定效果超过了单个拥挤剂的总和效果，即稳定效果本质上是非加性的。此外，与混合物中的其他拥挤剂相比，发现葡聚糖 40（在混合物中）具有最大的稳定化作用。换句话说，拥挤剂的小尺寸被观察到是稳定蛋白质的主导因素。
