Structure and Dynamics of Phospholipids in Micelles

磷脂提供了所有生物膜的基质，以及它们的代谢降解、运输 并在胶束中参与膜重塑。为了阐明它们的作用机制 并便于使用含有胶束的磷脂作为反应介质，它们的结构和 必须描述物理属性。拟议研究的长期目标是开发具有良好特性的 用于脂解酶研究的胶束底物。磷脂酶参与了 磷脂的代谢降解；它们还参与至关重要的生理过程 包括信号转导、血小板聚集、心脏收缩和兴奋以及前列腺素 生物合成。在这些事件中，水溶性脂解酶作用于水不溶底物，这些底物 以超分子聚集体(例如，混合胶束)组织。对其理化性质的阐明 了解脂-水界面及其对磷脂酶催化的影响将提高对磷脂酶的认识水平 这些酶的作用机制。 工作假说是，通过描绘胶束组分对 脂质-水界面的物理化学性质人们将能够设计具有靶向性的胶束 理化性质。为了验证这一假设，一种新开发的自旋交换EPR技术将是 与时间分辨荧光猝灭测量结合使用。1)站点定向旋转 标记和荧光报告基团将被用来确定烷链对 胶束的性质，2)极壳的物理化学参数将用 自旋探针二叔丁基氮氧化物(DTBN)，3)胶束与水之间的相间溶质交换 将通过自旋标记分配来测量，以及4)脂-水的性质之间的关系 界面和磷脂的水解率将建立使用一系列的分泌物 磷脂酶。如果新的EPR方法被证明是成功的 本文所研究的胶束，为将其应用于其他更复杂的超分子提供了可能 组装(如磷脂-胆盐混合胶束)，并可能成为一种通用技术 表征胶束聚集体。 与公共卫生相关：胶束在生物过程中发挥重要作用，包括药物输送 和膜功能。阐明它们的结构和性质将为以下方面提供有用的信息 更好地了解膜依赖的正常和病理细胞功能，包括细胞信号转导 炎症、过敏、细胞凋亡以及膜融合。

Phospholipids provide the matrix of all biological membranes, and their metabolic degradation, transportation and participation in membrane remodeling occur.in micelles. In order to elucidate the mechanisms of these processes and to facilitate the use of phospholipid containing micelles as reaction media their structure and physical properties must be delineated. The long term goal of the proposed research is to develop wellcharacterized micellar substrates for the study of lipolytic enzymes. Phospholipases are involved in metabolic degradation of phospholipids; they also participate in vitally important physiological processes including signal transduction, platelet aggregation, cardiac contraction and excitation, and prostaglandin biosynthesis. In these events water soluble lipolytic enzymes act on water insoluble substrates that are organized in supramolecular aggregates (e.g., mixed micelles). Elucidation of the physicochemical properties of the lipid-water interface and its effect on phospholipase catalysis will advance the level of understanding the mechanism of action of these enzymes. The working hypothesis is that by delineating the contributions of the micellar components to the physicochemical properties of the lipid-water interface one will be able to design micelles with targeted physicochemical properties. To test this hypothesis a newly developed spin exchange EPR technique will be used in conjunction with time-resolved fluorescence quenching measurements. 1) Site directed spin labelings, and fluorescent reporter groups will be used to determine the contribution of the alkyl chain to the properties of the micelle, 2) the physicochemical parameters of the polar shell will be determined using the spin probe di-tert.-butyl nitroxide (DTBN), 3) inter-phase solute exchange between the micelles and water will be measured by spin label partitioning, and 4) the relationship between the properties of the lipid-water interface and the rate of phospholipid hydrolysis will be established using a series of secretory phospholipase enzymes. Should the new EPR method prove to be successful in characterizing the mixed micelles here studied, it will open the possibility to apply it to other more complicated supramolecular assemblies (e.g. phospholipids-bile salt mixed micelles) and may become a general technique to characterize micellar aggregates. Relevance to Public Health: Micelles play an important role in biological processes, including drug delivery and membrane function. Elucidation of their structure and properties will provide useful information toward better understanding of membrane-dependent normal and pathological cell functions including cell signaling, inflammation, allergy, apoptosis, as well as membrane fusion.