Department of Soil and Water Sciences , China Agricultural University , Beijing 100193 , China.
Department of Environmental Science and Engineering , Fudan University , Shanghai 200433 , China.
Environ Sci Technol. 2019 Sep 3;53(17):10157-10165. doi: 10.1021/acs.est.9b02651. Epub 2019 Aug 16.
Adsorption kinetics and conformational changes of a model protein, bovine serum albumin (BSA, 0.1, 0.5, or 1.0 g/L), on the surface of hematite (α-FeO) particles in 39 ± 9, 68 ± 9, and 103 ± 8 nm, respectively, were measured using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. As the particle size increases, the amount of adsorbed BSA decreases, but the loss in the helical structure of adsorbed BSA increases due to the stronger interaction forces between adsorbed BSA and the larger particles. On 39 or 68 nm hematite particles, refolding of adsorbed BSA can be induced by protein-protein interactions, when the protein surface coverage exceeds certain critical values. Two-dimensional correlation spectroscopy (2D-COS) analysis of time-dependent ATR-FTIR spectra indicate that the increase in the amount of adsorbed BSA occurs prior to the loss in the BSA helical structure in the initial stage of adsorption processes, whereas an opposite sequence of the changes to BSA conformation and surface coverage is observed during the subsequent refolding processes. Desorption experiments show that replacing the protein solution with water can quench the refolding, but not the unfolding, of adsorbed BSA. A kinetic model was proposed to quantitatively describe the interplay of adsorption kinetics and conformational change, as well as the effects of particle size and initial protein concentration on the rate constants of elementary steps in protein adsorption onto a mineral surface.
采用衰减全反射傅里叶变换红外光谱（ATR-FTIR）技术，分别测量了牛血清白蛋白（BSA，浓度为 0.1、0.5 和 1.0 g/L）在尺寸分别为 39±9、68±9 和 103±8nm 的针铁矿（α-FeO）颗粒表面的吸附动力学和构象变化。随着颗粒尺寸的增大，吸附的 BSA 量减少，但由于吸附的 BSA 与较大颗粒之间的相互作用力更强，导致吸附 BSA 的螺旋结构损失增加。在 39 或 68nm 的针铁矿颗粒上，当蛋白质表面覆盖率超过一定的临界值时，吸附 BSA 之间的蛋白质-蛋白质相互作用可以诱导其重新折叠。ATR-FTIR 谱的时间依赖性二维相关光谱（2D-COS）分析表明，在吸附过程的初始阶段，吸附 BSA 量的增加先于 BSA 螺旋结构的损失，而在随后的重新折叠过程中，BSA 构象和表面覆盖率的变化则呈现相反的顺序。解吸实验表明，用去离子水替代蛋白质溶液可以猝灭吸附 BSA 的重新折叠，但不能猝灭其解折叠。提出了一个动力学模型，以定量描述吸附动力学和构象变化之间的相互作用，以及颗粒尺寸和初始蛋白质浓度对蛋白质在矿物表面吸附的基本步骤速率常数的影响。
