CYTOSOLIC CA2+ IONOPHORES FOR FLUORESCENCE & 19F NMR

一系列改进的钙离子螯合剂， 核磁共振和荧光成像将被合成和评估 因为它们的吸收和发射特性以及它们的 结合Ca2+的能力。 所提出的螯合剂包括 具有期望的高量子产率和可见光的荧光团 波长吸收和发射。 荧光团附着在 一种类似EGTA的结构， 对Ca2+的特异性超过Mg2+和其它二价金属离子。 因此，所提出的Ca2+指示剂将具有改善的光学性能。 与目前使用的quin2和indo-1相比， 除了荧光团之外，结构上相似。 此外该 指示剂将被氟取代的19F NMR检测。 的 当醋酸盐 基团被酯化，并可通过以下方式再转化为乙酸酯形式： 细胞内的胞质酯酶。 因此，捕获的螯合剂可以 用于跟踪细胞内钙离子浓度的变化 浓度，（Ca2+）i，作为响应时间的函数 各种干扰影响。 细胞内钙目前 作为第二信使， 触发并调节细胞活化。 第一阶段的工作包括 连接到F的氨基萘并吡喃酮骨架的合成 通过二醚骨架的取代的环。 在第二阶段， 合成将完成和评价的光学常数 并计算钙离子结合常数。 最 有希望的指标将测试细胞膜 渗透性和作为19F NMR的断层成像剂。

A series of improved Ca2+ chelating agents which can be used for NMR and fluorescence imaging will be synthesized and evaluated for their absorption and emission characteristics as well as their ability to bind Ca2+. The proposed chelators incorporate fluorophores which have desirable high quantum yields and visible wavelength absorption and emission. The fluorophore is attached to an EGTA-like structure which is known to have great specificity for Ca2+ over Mg2+ and other divalent metal ions. The proposed Ca2+ indicators will thus have improved optical characteristics over currently used quin2 and indo-1, which they resemble structurally except for the fluorophore. In addition, the indicator will be fluorine substitute of 19F NMR detection. The indicators will be cell membrane permeable when the acetate groups are esterified, and reconvertible to the acetate form by cytosolic esterases inside the cell. Thus the trapped chelator can be used to follow concentration changes in intracellular calcium concentration, (Ca2+)i, as a function of time in response to various perturbing influences. Intracellular calcium is currently the subject of wide-spread interest as a second messenger that triggers and regulates cell activation. Phase I work involves synthesis of the amino napthopyrone skeleton linked to the F substituted ring through the diether backbone. In Phase II the synthesis will be completed and evaluation of optical constants and Ca2+ binding constants will be carried out. The most promising indicators will be tested for cell membrane permeability and as tomographic imaging agents for 19F NMR.