Želinská Katarína, Gallová Jana, Huláková Silvia, Uhríková Daniela, Ivankov Oleksandr
Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia.
Gen Physiol Biophys. 2020 Mar;39(2):107-122. doi: 10.4149/gpb_2019056.
Solubilisation of model membranes of dioleoylphosphatidylcholine (DOPC) and DOPCcholesterol (CHOL) induced by surfactant N,N-dimethyl-1-dodecanamine-N-oxide (DDAO) was studied. At the maintained pH ~ 7.5, the DDAO molecules are in their neutral state with respect to the pK ~ 5. Pore formation in lipid bilayer was studied by fluorescence probe leakage method. The changes in the size of lipid aggregates upon increasing DDAO concentration were followed turbidimetrically. Effective ratio Re at different steps of the solubilisation process was determined. The molar partition coefficient of DDAO in case of the DOPC membrane is Kp = 2262 ± 379, for DOPC-CHOL membrane Kp = 2092 ± 594. Within the experimental error, the partition coefficient, as well as effective ratios Re, are not considerably influenced when one third of DOPC molecules is substituted with CHOL (DOPC:CHOL = 2:1). Constituents of buffer (50 mmol/dm3 PBS, 150 mmol/dm3 NaCl) caused aggregation of DOPC and DOPC-CHOL unilamellar liposomes at zero and low DDAO concentration, as was shown by SANS, turbidimetry and DIC microscopy. After solubilisation of bilayer structures by surfactant, mixed DOPC-DDAO and DOPC-CHOL-DDAO micelles with the shape of cylinders with elliptical cross section were detected.
研究了表面活性剂N,N-二甲基-1-十二烷基胺-N-氧化物（DDAO）诱导的二油酰磷脂酰胆碱（DOPC）和DOPC-胆固醇（CHOL）模型膜的增溶作用。在pH约为7.5时，DDAO分子相对于pK约为5处于中性状态。通过荧光探针泄漏法研究了脂质双层中的孔形成。通过比浊法跟踪随着DDAO浓度增加脂质聚集体大小的变化。测定了增溶过程不同步骤的有效比Re。在DOPC膜的情况下，DDAO的摩尔分配系数为Kp = 2262 ± 379，对于DOPC-CHOL膜，Kp = 2092 ± 594。在实验误差范围内，当三分之一的DOPC分子被CHOL取代（DOPC:CHOL = 2:1）时，分配系数以及有效比Re没有受到显著影响。如小角中子散射（SANS）、比浊法和微分干涉对比（DIC）显微镜所示，缓冲液成分（50 mmol/dm3 PBS，150 mmol/dm3 NaCl）在DDAO浓度为零和低浓度时会导致DOPC和DOPC-CHOL单层脂质体聚集。在用表面活性剂增溶双层结构后，检测到具有椭圆形横截面的圆柱形混合DOPC-DDAO和DOPC-CHOL-DDAO胶束。
