Structure and Thermotropic Phase Behavior of a Homologous Series of Bioactive N-Acyldopamines
Structure and Thermotropic Phase Behavior of a Homologous Series of Bioactive N-Acyldopamines
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DOI：
10.1021/jp402750m
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发表时间：
2013-07-25
影响因子：
3.3
通讯作者：
Swamy, Musti J.
中科院分区：
文献类型：
--
作者：
Reddy, S. Thirupathi;Tarafdar, Pradip K.;Swamy, Musti J.
N-酰基多巴胺 (NADA) 存在于哺乳动物神经组织中，具有有趣的生物学和药理学特性。在本研究中，合成并表征了一系列具有不同酰基链（n = 12-20）的同源 NADA。差示扫描量热研究表明，在干燥状态下，NADA 的转变温度、焓和熵表现出奇偶交替，偶数链长系列对应的值略高。偶数和奇数链长 NADA 都显示出跃迁焓和熵对链长的线性依赖性。然而，尽管转变焓和熵表现出线性依赖性，但在水合时的量热特性中没有观察到奇偶交替。线性最小二乘分析得出每个亚甲基对转变焓和熵以及相应的最终贡献贡献的增量值。 N-月桂酰多巴胺 (NLDA) 在单斜空间群 C2/c 中结晶，晶胞中有八个对称相关分子。单晶 X 射线衍射研究表明，NLDA 分子以双层形式组织，分子头对头（和尾对尾）排列。相对层的多巴胺部分的羟基之间的水介导的氢键和同一层中相邻分子的酰胺基之间的N-H中心点中心点中心点O氢键稳定了晶体堆积。这些结果为研究 NADA 与其他膜脂的相互作用提供了热力学和结构基础，这有望为了解它们在体内如何发挥作用（例如作为调节疼痛的信号分子）提供线索。
N-Acyldopamines (NADAs), which are present in mammalian nervous tissues, exhibit interesting biological and pharmacological properties. In the present study, a homologous series of NADAs with varying acyl chains (n = 12-20) have been synthesized and characterized. Differential scanning calorimetric studies show that in the dry state the transition temperatures, enthalpies, and entropies of NADAs exhibit odd-even alternation with the values corresponding to the even chain length series being slightly higher. Both even and odd chain length NADAs display a linear dependence of the transition enthalpies and entropies on the chain length. However, odd-even alternation was not observed in the calorimetric properties upon hydration, although the transition enthalpies and entropies exhibit linear dependence. Linear least-squares analyses yielded incremental values contributed by each methylene group to the transition enthalpy and entropy and the corresponding end contributions. N-Lauroyldopamine (NLDA) crystallized in the monoclinic space group C2/c with eight symmetry-related molecules in the unit cell. Single-crystal X-ray diffraction studies show that NLDA molecules are organized in the bilayer form, with a head-to-head (and tail-to-tail) arrangement of the molecules. Water-mediated hydrogen bonds between the hydroxyl groups of the dopamine moieties of opposing layers and N-H center dot center dot center dot O hydrogen bonds between the amide groups of adjacent molecules in the same layer stabilize the crystal packing. These results provide a thermodynamic and structural basis for investigating the interaction of NADAs with other membrane lipids, which are expected to provide clues to understand how they function in vivo, e.g., as signaling molecules in the modulation of pain.