State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
J Phys Chem B. 2011 Jun 23;115(24):7744-50. doi: 10.1021/jp200778b. Epub 2011 Jun 1.
In this work, the pore size-dependent PPL diffusion and protein distribution in SBA-15 support have been investigated in detail by confocal laser scanning microscopy (CLSM) and X-ray diffraction (XRD) observations in combination with hindered diffusion simulation, intraparticle diffusion analysis, and apparent kinetics calculation. The CLSM observations indicate porcine pancreatic lipase (PPL) diffuses partly into the pores with a diameter of 5.6 nm and much deeper into the pores with a diameter of 8.0 or 9.7 nm. PPL distribution along the pore length has been simulated by hindered diffusion model and the result coincides well with CLSM observations. Besides pore diffusion, boundary resistance is revealed by the intraparticle diffusion analysis of adsorption data. The populations of PPL adsorbed inside the pores or on the external surface are estimated. A higher PPL uptake is found in the 8.0 nm than 9.7 nm pores, indicative of the existence of an optimal pore size to match the protein dimension for maximum adsorption capacity. The so-called "confinement" of PPL in the mesoporous supports, revealed by the XRD observation and intraparticle diffusion analysis above, is further confirmed by apparent kinetics calculation.
在这项工作中，通过共焦激光扫描显微镜（CLSM）和 X 射线衍射（XRD）观察，结合受阻扩散模拟、颗粒内扩散分析和表观动力学计算，详细研究了介孔 SBA-15 载体中孔径依赖性的 PPL 扩散和蛋白质分布。CLSM 观察表明，猪胰脂肪酶（PPL）部分扩散到直径为 5.6nm 的孔中，并更深入地扩散到直径为 8.0nm 或 9.7nm 的孔中。通过受阻扩散模型模拟了 PPL 在孔长方向上的分布，结果与 CLSM 观察结果吻合较好。除了孔扩散之外，吸附数据的颗粒内扩散分析揭示了边界阻力。估计了 PPL 在孔内或外表面上的吸附种群。在 8.0nm 孔中发现了更高的 PPL 摄取量，这表明存在一个最佳的孔径，以匹配蛋白质尺寸，以获得最大的吸附容量。通过上述 XRD 观察和颗粒内扩散分析揭示的 PPL 在介孔载体中的所谓“限制”，通过表观动力学计算进一步得到证实。
