动态Monte Carlo模拟蛋白质与微滤膜相互作用及其对微滤过程的影响

Dynamic Monte Carlo simulation of protein-membrane interaction and its implication on micro-filtration process

构建了二维晶格蛋白质-微滤膜疏水相互作用模型,采用动态Monte Carlo方法模拟了微滤膜污染过程及其受膜孔径、蛋白质浓度和蛋白质结构特性等因素的影响。模拟结果显示:微滤过程中膜通量的变化呈现快速下降、缓慢下降和平台期3个阶段。小孔径微滤膜的滤阻从以膜孔阻力为主转变为以饼层阻力为主;而大孔径微滤膜的滤阻则以膜孔阻力为主。提高蛋白质浓度会强化滤阻从膜孔阻力向饼层阻力的转变。在微滤过程中,蛋白质会因疏水相互作用在膜孔内发生构象转换,进而发生不可逆吸附并形成多层堆积,导致膜污染和通量下降,提高蛋白质的构象稳定性可以显著降低其对微滤膜的污染。分子模拟结果与文献报道的实验结果和理论模型相符,所提供的微观信息对于微滤过程优化和微滤膜设计具有参考作用。

A two-dimensional lattice model that highlights the hydrophobic interaction between protein and micro-filtration（MF）membrane was presented for dynamic Monte Carlo simulation of the membrane fouling process.The effect of membrane pore size,protein concentration and structure on membrane fouling was examined.It was shown that the MF process could be divided into three stages according to the changes in the trans-membrane flux,i.e.,rapid declining,slow declining and quasi-steady-state.For the MF membrane with a small pore size,cake resistance became dominating while the pore resistance contributed less to the overall filtration resistance along with the filtration process,while the filtration using the membrane with a large pore size was dominated by the pore resistance.The increase of protein concentration accelerated the shift of the dominating role from pore resistance to cake resistance.The hydrophobic interaction between membrane and protein may lead to the unfolding of protein,the enhancement of the irreversible multi-layer adsorption onto membrane surface,and consequently,the reduction of trans-membrane flux.The enhancement of protein structure characterized by hydrophobic core may repress the adsorption and this could be accomplished by choosing an appropriate solution.The simulation results agreed well with both experimental investigation and theoretical models reported elsewhere.The molecular insight of the MF process provided by the above simulation is helpful for the optimization of the MF process and design of new MF membrane.