l -Phenylalanine Partitioning Mechanisms in Model Biological Membranes
l -Phenylalanine Partitioning Mechanisms in Model Biological Membranes
复制标题
模型生物膜中的l-苯丙氨酸分配机制
DOI：
10.1021/acs.jpcb.2c08582
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Walker, Robert A.
中科院分区：
文献类型：
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作者：
Duncan, Katelyn M.;Trousdale, Rhys C.;Gonzales, Cristina N.;Steel, William H.;Walker, Robert A.
用时间分辨荧光光谱结合差示扫描量热法(DSC)研究了L-苯丙氨酸与磷脂酰胆碱囊泡的相互作用。这项工作解决了关于l-Phe对脂泡双层的亲和力、l-Phe分配对双层性质的影响、L-Phe在脂双层中的溶剂化以及该局部溶剂化环境中l-Phe的量等悬而未决的问题。DSC数据表明，l-Phe降低了饱和磷脂酰胆碱双层从凝胶熔融到液晶状态所需的热量，但不改变转变温度(TGel-Lc)。时间分辨发射表明，与l-Phe在水溶液中的溶剂化程度相对应，在低温下只有1-Phe的寿命。在接近TGel-lc的温度下，第二个更短的寿命出现，它被分配给已经嵌入到膜中的l-Phe，随着水开始渗透到脂双层中，它变得水合。这一新的寿命归因于双分子层的极性头基团区域中的构象受限旋转体，并且占发射幅度的30%。报道的二棕榈酰磷脂酰胆碱(DPPC，16：0)脂泡的结果与观察到的二肉豆蔻酰磷脂酰胆碱(DMPC，14：0)和二硬脂酰磷脂酰磷脂酰胆碱(DSPC，18：0)囊泡的作用相似。综上所述，这些结果形成了HOWL-Phe与模型生物膜相关联的完整且引人注目的图景。此外，这种检测氨基酸分配到膜中以及由此产生的溶剂化力的方法为研究膜可溶性多肽和选定的膜蛋白的结构和化学提供了新的策略。
Time-resolved fluorescence spectroscopy in combination with differential scanning calorimetry (DSC) was used to study the chemical interactions that occur whenl-phenylalanine is introduced to solutions containing phosphatidylcholine vesicles. Studies reported in this work address open questions aboutl-Phe’s affinity for lipid vesicle bilayers, the effects ofl-Phe partitioning on bilayer properties,l-Phe’s solvation within a lipid bilayer, and the amount ofl-Phe within that local solvation environment. DSC data show thatl-Phe reduces the amount of heat necessary to melt saturated phosphatidylcholine bilayers from their gel to liquid-crystalline state but does not change the transition temperature (Tgel-lc). Time-resolved emission shows only a singlel-Phe lifetime at low temperatures corresponding tol-Phe remaining solvated in aqueous solution. At temperatures close toTgel-lc, a second, shorter lifetime appears that is assigned tol-Phe already embedded within the membrane that becomes hydrated as water starts to permeate the lipid bilayer. This new lifetime is attributed to a conformationally restricted rotamer in the bilayer’s polar headgroup region and accounts for up to 30% of the emission amplitude. Results reported for dipalmitoylphosphatidylcholine (DPPC, 16:0) lipid vesicles prove to be general, with similar effects observed for dimyristoylphosphatidylcholine (DMPC, 14:0) and distearoylphosphatidylcholine (DSPC, 18:0) vesicles. Taken together, these results create a complete and compelling picture of howl-Phe associates with model biological membranes. Furthermore, this approach to examining amino acid partitioning into membranes and the resulting solvation forces points to new strategies for studying the structure and chemistry of membrane-soluble peptides and selected membrane proteins.