申请人:——
公开号:US05446186A1
公开(公告)日:1995-08-29
The synthesis and compound of a new caged calcium which is an ortho-nitrophenyl derivative of EGTA and various intermediates. It is synthesized in ten steps and 24% overall yield. The photosensitive chelator, nitrophenyl-EGTA, has a K.sub.d for Ca.sup.2+ of 80 nM and for Mg.sup.2+ of 8.8 mM. Upon exposure to ultra-violet light (in the region of 350 nm), the chelator is cleaved, yielding iminodiacetic acid photoproducts with known low Ca-affinity (K.sub.d =1 mM). The quantum yield of photolysis of nitrophenyl-EGTA in the presence of Ca.sup.a+ is 0.23 and in the absence of Ca.sup.2+ is 0.20. In experiments with chemically skinned skeletal muscle fibers, a fully relaxed fiber equilibrated with nitrophenyl-EGTA:Ca.sup.2+ complex, in the presence of physiological [Mg.sup.2+ ] (i.e. 1.0 mM), produced maximal contraction after a single flash from a frequency doubled ruby laser (347 nm). Half-maximal tension was achieved in 18 ms at 15.degree. C. Nitrophenyl-EGTA provides a new tool for the investigation of the mechanism of Ca.sup.2+ -dependent physiological processes, since under conditions of normal intracellular Ca.sup.2+ and Mg.sup.2+ ions, only Ca.sup.2+ ions are bound by the photolabile chelator and on illumination are released rapidly and in high photochemical yield.
一种新的笼式钙配合物及其合成方法和化合物,该配合物是EGTA的邻硝基苯基衍生物和各种中间体。它经过十个步骤合成,总产率为24%。光敏螯合剂硝基苯基-EGTA的Ca2 +的K.sub.d为80 nM,Mg2 +的K.sub.d为8.8 mM。在紫外光(在350 nm区域)照射下,螯合剂被裂解,产生已知低Ca亲和力(K.sub.d =1 mM)的亚胺二乙酸光产物。硝基苯基-EGTA的光解量子产率在Ca2 +存在时为0.23,在Ca2 +不存在时为0.20。在化学剥离的骨骼肌纤维实验中,完全松弛的纤维在生理[Mg2 +](即1.0 mM)存在下,平衡硝基苯基-EGTA:Ca2 +复合物,在来自倍频红宝石激光器的单个闪光后产生最大收缩。在15℃下,半最大张力在18 ms时达到。硝基苯基-EGTA为研究Ca2 +-依赖性生理过程的机制提供了一种新工具,因为在正常细胞内Ca2 +和Mg2 +离子的条件下,仅Ca2 +离子被光敏螯合剂结合,并在照射时迅速释放并具有高光化学产率。