Roles of α-methyl trans-cyclopropane groups in behavior of mixed mycolic acid monolayers
Roles of α-methyl trans-cyclopropane groups in behavior of mixed mycolic acid monolayers
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α-甲基反式环丙烷基团在混合分枝菌酸单层行为中的作用
DOI：
10.1016/j.bbamem.2018.10.019
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Noguchi Hiroki
中科院分区：
文献类型：
--
作者：
Villeneuve Masumi;Noguchi Hiroki
研究了 1 型 α-(α-) 和酮-霉菌酸 (MA) 的混合 Langmuir 膜，以了解含有酮-MA 的 α-甲基反式-环丙烷在确定单层的物理和化学性质中的作用。在恒定摩尔分数下测量表面压力 (π) 与平均分子面积 (A) 等温线，该摩尔分数定义为在 25°C 和 37°C 下酮-MA 摩尔浓度与 α-MA 和酮-MA (Xketo) 总摩尔浓度的比率。比较不同 Xketo 在固定 π 值下的混合单层的 A 和弹性模量 (E)。在富含酮-MA的单层中，A值远大于α-MA和酮-MA的总面积值，而E值与固体酮-MA单层的值接近。A和E还与含酮-MA的α-甲基反式环丙烷的摩尔分数作图，表明α-甲基反式环丙烷基团稳定了单层中分枝菌酸的W型构象，使其呈固态。状态。此外，实验结果与不同菌株细胞壁MA中α-甲基反式环丙烷含量的比较表明，反式环丙烷含量的比例对于确定混合MA层的性质很重要。
Mixed Langmuir films of type 1 alpha-(α-) and keto-mycolic acids (MAs) were investigated to understand the roles ofα-methyltrans-cyclopropane containing keto-MA in determining the physical and chemical properties of the monolayers. Surface pressure (π) vs. mean molecular area (A) isotherms were measured at constant mole fractions defined as the ratio of the keto-MA molarity to the total molarity ofα-MA and keto-MA (Xketo) at 25 °C and 37 °C.Aand the elastic modulus (E) of the mixed monolayer were compared for differentXketoat fixedπvalues. In keto-MA rich monolayers,Avalues were much larger than values of the combined areas ofα-MA and keto-MA, while theEvalues were close to those of solid keto-MA monolayers.AandEwere also plotted against the mole fraction ofα-methyltrans-cyclopropane containing keto-MA, which showed that theα-methyl trans-cyclopropane group stabilized the W-form conformation of mycolic acids in monolayers, and rendered them solid state. Furthermore, a comparison of the experimental results and theα-methyltrans-cyclopropane content in cell-wall MAs from various strains indicated that the ratio oftrans-cyclopropane content was important in determining the nature of the mixed MA layer.