PHOTOLABILE CHELATORS FOR THE RAPID PHOTORELEASE OF DIVALENT-CATIONS
PHOTOLABILE CHELATORS FOR THE RAPID PHOTORELEASE OF DIVALENT-CATIONS
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DOI：
10.1073/pnas.85.17.6571
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发表时间：
1988-09-01
影响因子：
11.1
通讯作者：
ELLISDAVIES, GCR
中科院分区：
文献类型：
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作者：
KAPLAN, JH;ELLISDAVIES, GCR
最近合成的二价阳离子的光不稳定螯合剂的性质进行了描述，其中的Ca 2+的亲和力的变化由一些5个数量级的照明。化合物1-（2-硝基-4，5-二甲氧基苯基）-N，N，N“，N”-四[（氧羰基）甲基]-1，2-乙二胺（DM-nitrophen）与Ca 2+结合（Kd = 0.001）。5.0. times. 10-9 M）和Mg 2+（Kd apprxeq. 2.5. times. 10-6 M）具有相对高的亲和力。在将DM-硝基菲-Ca 2+复合物暴露于350-nm范围内的UV光时，螯合剂被裂解，产生对Ca具有低得多的亲和力的亚氨基二乙酸产物（Kd = 0.0001）。3倍。10-3 M）和游离[Ca 2 +]增加。Ca 2+释放的量子产率为0.18。在化学皮肤骨骼肌纤维的实验中，一个完全放松的纤维与DM-nitrophen-Ca 2+复合物平衡后产生最大的收缩后，从倍频红宝石激光（347 nm）的单闪光。半最大张力达到约40 ms，比从无Ca 2+溶液快速变为含Ca 2+溶液后获得的快约5倍。在实验中重新密封的人红细胞鬼，照射鬼含有DM-nitrophen-Ca 2+复合物激活Ca 2+依赖的K+外流途径，这是没有观察到在照明的情况下。DM-nitrophen是足够稳定和光不稳定的，可用作笼状钙（或笼状镁）的快速光引发的二价阳离子依赖的过程在一个广泛的浓度范围内与显着增加的时间分辨率比传统的混合方法。
The properties of a recently synthesized photolabile chelator for divalent cations are described, the affinity of which for Ca2+ changes by some 5 orders of magnitude on illumination. The compound 1-(2-nitro-4,5-dimethoxyphenyl)-N,N,N'',N''-tetrakis[(oxycarbonyl)methyl]-1,2-ethanediamine (DM-nitrophen) binds Ca2+ (Kd .apprxeq. 5.0 .times. 10-9 M) and Mg2+ (Kd .apprxeq. 2.5 .times. 10-6 M) with relatively high affinities. On exposure of the DM-nitrophen-Ca2+ complex to UV light in the 350-nm range, the chelator is cleaved yielding iminodiacetic products with a much lower affinity for Ca (Kd .apprxeq. 3 .times. 10-3 M) and the free [Ca2+] increases. The quantum yield for Ca2+ release is 0.18. In experiments with chemically skinned skeletal muscle fibers, a fully relaxed fiber equilibrated with DM-nitrophen-Ca2+ complex produced maximal contraction after a single flash from a frequency-doubled ruby laser (347 nm). Half-maximal tension was achieved in .apprxeq. 40 ms, some 5 times faster than that obtained after a rapid solution change from a Ca2+-free to a Ca2+-containing solution. In experiments with resealed human erythrocyte ghosts, irradiation of ghosts containing the DM-nitrophen-Ca2+ complex activates a Ca2+-dependent K+ efflux pathway, which is not observed in the absence of illumination. DM-nitrophen is sufficiently stable and photolabile to be used as a caged Ca (or caged Mg) for the rapid photoinitiation of divalent cation-dependent processes over a wide concentration range with a significant increase in temporal resolution over conventional mixing methods.