Instituto Nacional del Carbón (INCAR-CSIC), c/Francisco Pintado Fe 26, 33011 Oviedo, Spain.
Instituto Nacional del Carbón (INCAR-CSIC), c/Francisco Pintado Fe 26, 33011 Oviedo, Spain.
J Colloid Interface Sci. 2018 Feb 1;511:27-38. doi: 10.1016/j.jcis.2017.09.091. Epub 2017 Sep 23.
The adsorption of cytochrome c in water onto organic and carbon xerogels with narrow pore size distributions has been studied by carrying out transient and equilibrium batch adsorption experiments. It was found that equilibrium adsorption exhibits a quasi-Langmuirian behavior (a g coefficient in the Redlich-Peterson isotherms of over 0.95) involving the formation of a monolayer of cyt c with a depth of ∼4nm on the surface of all xerogels for a packing density of the protein inside the pores of 0.29gcm. A load-dependent surface diffusion model (LDSDM) has been developed and numerically solved to fit the experimental kinetic adsorption curves. The results of the LDSDM show better fittings than the standard homogeneous surface diffusion model. The value of the external mass transfer coefficient obtained by numerical optimization confirms that the process is controlled by the intraparticle surface diffusion of cyt c. The surface diffusion coefficients decrease with increasing protein load down to zero for the maximum possible load. The decrease is steeper in the case of the xerogels with the smallest average pore diameter (∼15nm), the limit at which the zero-load diffusion coefficient of cyt c also begins to be negatively affected by interactions with the opposite wall of the pore.
已通过进行瞬态和平衡批处理吸附实验研究了水中小分子细胞色素 c 在具有窄孔径分布的有机和碳干凝胶中的吸附。结果表明，平衡吸附表现出准朗缪尔行为（Redlich-Peterson 等温线中的 g 系数大于 0.95），涉及在所有干凝胶表面上形成单层 cyt c，其深度约为 4nm，对于孔内蛋白质的堆积密度为 0.29gcm。已经开发并数值求解了负载相关表面扩散模型（LDSDM）以拟合实验动力学吸附曲线。LDSDM 的结果比标准均匀表面扩散模型具有更好的拟合度。数值优化得到的外部传质系数值证实该过程受 cyt c 的颗粒内表面扩散控制。表面扩散系数随蛋白质负载的增加而降低，直至达到最大可能负载时为零。在平均孔径最小（约 15nm）的干凝胶中，下降更为陡峭，此时 cyt c 的零载扩散系数也开始受到与孔相反壁相互作用的负面影响。
