Kumar Manish, Grzelakowski Mariusz, Zilles Julie, Clark Mark, Meier Wolfgang
Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, Urbana, IL 61801, USA.
Proc Natl Acad Sci U S A. 2007 Dec 26;104(52):20719-24. doi: 10.1073/pnas.0708762104. Epub 2007 Dec 11.
The permeability and solute transport characteristics of amphiphilic triblock-polymer vesicles containing the bacterial water-channel protein Aquaporin Z (AqpZ) were investigated. The vesicles were made of a block copolymer with symmetric poly-(2-methyloxazoline)-poly-(dimethylsiloxane)-poly-(2-methyloxazoline) (PMOXA(15)-PDMS(110)-PMOXA(15)) repeat units. Light-scattering measurements on pure polymer vesicles subject to an outwardly directed salt gradient in a stopped-flow apparatus indicated that the polymer vesicles were highly impermeable. However, a large enhancement in water productivity (permeability per unit driving force) of up to approximately 800 times that of pure polymer was observed when AqpZ was incorporated. The activation energy (E(a)) of water transport for the protein-polymer vesicles (3.4 kcal/mol) corresponded to that reported for water-channel-mediated water transport in lipid membranes. The solute reflection coefficients of glucose, glycerol, salt, and urea were also calculated, and indicated that these solutes are completely rejected. The productivity of AqpZ-incorporated polymer membranes was at least an order of magnitude larger than values for existing salt-rejecting polymeric membranes. The approach followed here may lead to more productive and sustainable water treatment membranes, whereas the variable levels of permeability obtained with different concentrations of AqpZ may provide a key property for drug delivery applications.
研究了含有细菌水通道蛋白水通道蛋白Z（AqpZ）的两亲性三嵌段聚合物囊泡的渗透性和溶质传输特性。这些囊泡由具有对称聚（2-甲基恶唑啉）-聚（二甲基硅氧烷）-聚（2-甲基恶唑啉）（PMOXA(15)-PDMS(110)-PMOXA(15)）重复单元的嵌段共聚物制成。在停流装置中对纯聚合物囊泡施加向外的盐梯度进行光散射测量表明，聚合物囊泡具有高度的不渗透性。然而，当掺入AqpZ时，观察到水生产率（单位驱动力的渗透率）大幅提高，高达纯聚合物的约800倍。蛋白质-聚合物囊泡的水传输活化能（E(a)）为3.4千卡/摩尔，与脂质膜中水通道介导的水传输报道值相当。还计算了葡萄糖、甘油、盐和尿素的溶质反射系数，表明这些溶质被完全截留。掺入AqpZ的聚合物膜的生产率比现有的拒盐聚合物膜的值至少大一个数量级。这里采用的方法可能会导致生产效率更高、更可持续的水处理膜，而不同浓度的AqpZ获得的不同渗透率水平可能为药物递送应用提供关键特性。
