Stereospecific Organic Reactions in Functionalized Synthetic Bilayer Membranes

1.合成多肽脂的聚集形态。--将氨基酸残基作为结构成分，设计了在水介质中形成化学和形态稳定的单壁囊泡的多肽脂类。成功地制备了具有阳离子、阴离子和非离子头部的多肽脂类，并考察了它们在水介质中的形态行为。特别是，首次用这些合成脂质构建了立方相和六方相的非双层聚集体。单壁小泡的融合行为。--非离子和阴离子多肽脂等摩尔混合物形成的窦壁小泡通过形成非双层聚集体，通过调节pH或温度进行融合。当加入具有相反电荷的离子聚合物时，具有离子头部部分的单壁囊泡瞬间融合。依赖维生素的酶的功能模型。--一个全酶模型，由单壁小泡的多肽脂和疏水性维生素lt；B_6&gt；催化氨基酸和具有周转行为的酮酸之间的转氨基反应。在此首次获得了一种人工转氨酶。维生素B_(12)依赖酶的功能模型--一个全酶模型，由单壁小泡的肽脂和疏水性维生素-lt；B_(12)&gt；催化碳-骨架重排，其方式与甲基丙二酰辅酶A变位酶观察到的方式相同。

1. Aggregate Morphology of Synthetic Peptide Lipids. -- Peptide lipids, which can form chemically and morphologically stable single-walled vesicles in aqueous media, were desinged by incorporation of amino acid residues as their structural components. Those peptide lipids having cationic, anionic, and nonionic head moieties were successfully prepared, and their morphological behavior in aqueous media was examined. In particular, nonbilayer aggregates, cubic and hexagonal phases, were constructed for the first time with these synthetic lipids.2. Fusion Behavior of Single-Walled Vesicles. -- Sintle-walled vesicles formed with equimolar mixtures of nonionic and anionic peptide lipids underwent fusion by adjusting pH or temperature via formation of nonbilayer aggregates. Single-walled vesicles having ionic head moieties underwent fusion instantaneously upon addition of ionic polymers having the opposite charges.3. Functional Model of Vitamin <B_6> -dependent Enzyme. -- A holoenzyme model formed with single-walled vesicles of the peptide lipid and a hydrophobic vitamin <B_6> catalyzed the transamination reaction between an amino acid and a keto acid with turnover behavior. Here, an artificial transaminase was obtained for the first time.4. Functional Model of Vitamin <B_(12)> -dependent Enzyme. -- A holoenzyme model formed with single-walled vesicles of the peptide lipid and a hydrophobic vitamin <B_(12)> catalyzed the carbon-skeletal rearrangement in a manner as observed with methylmalonyl-CoA mutase.