Rate of release of Ca2+ following laser photolysis of the DM-nitrophen-Ca2+ complex.
Rate of release of Ca2+ following laser photolysis of the DM-nitrophen-Ca2+ complex.
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DM-硝基酚-Ca2 复合物激光光解后 Ca2 的释放速率。
DOI：
10.1021/bi00152a023
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发表时间：
1992
期刊：
影响因子：
2.9
通讯作者：
Kaplan,JH
中科院分区：
文献类型：
--
作者：
McCray,JA;Fidler-Lim,N;Ellis-Davies,GC;Kaplan,JH
摘要：利用光降解螯合剂DM-nitrophen的脉冲光解测定Ca2+的释放速率对于其在时间分辨率生理研究中的应用是重要的：底物或效应物的释放速率应该比它们启动的过程快。利用倍频红宝石激光器（发射波长为347 nm，能量约为10-20 mJ）发出的50 ns脉冲对dm -硝基苯进行闪光光解，可产生短寿命的光致变色中间体或酸-硝基中间体。pH值为6.9时，dm - nitrophenen及其Ca2+配合物的双指数衰减（n/2值分别为24和570 ms， 32和220 p&），而dm - nitrophenen - mg2 +配合物的单指数衰减（n/2= 31 ms）。只有dm - nitrophen2 - ca2 +的光化学反应对pH值敏感（单指数衰减，在pH值7.9和8.9时n/2~ 115 ms）。使用Ca2+敏感的异色染料antipyrylazo III与dm -硝基苯-Ca2+的脉冲光解相结合，可以建立Ca2+释放的半衰期上限，约为180 ps （Ca2+与染料的结合速率可能决定速率）。然而，Ca2+光释放的速率可能比这快。因此，dm -硝基苯-Ca2+复合物在光解过程中释放Ca2+的速度足够快，可以用于研究许多Ca2+依赖的生理过程，并且比传统的混合方法具有更高的动力学分辨率。许多生理过程发生在短时间内（微秒到毫秒的时间域）。肌肉收缩、突触传递、激素分泌等是对各种效应分子的短暂、局部波动作出反应的一些过程。在许多情况下，该过程的动力学分辨率受到扩散混合的限制
Revised Manuscript Received June 29, 1992 abstract: The determination of the rate of release of Ca2+ by pulsed photolysis of the photolabile chelator DM-nitrophen is important for its use in time-resolved physiologicalstudies: the rate of substrate or effector release should be faster than the processes they initiate. Flash photolysis of DM-nitrophen using a 50-ns pulse from a frequency-doubled ruby laser (with emission at 347 nm having energy of ca. 10-20 mJ) yields short-lived photochromic or aci-nitro intermediates. At pH 6.9, double-exponential decay of a photo-chromic intermediate was observed for DM-nitrophen itself and its Ca2+ complex (n/2 values of 24 and 570 ms, and 32 and 220 p& respectively), while only monoexponential decay of the DM-nitrophen-Mg2+ complex was detected (n/2= 31 ms). Only the photochemistry of DM-nitrophen-Ca2+ was found to be pH sensitive (monoexponential decay, n/2~ 115 ms at pH 7.9 and 8.9). Use of the Ca2+-sensitive met-allochromic dye antipyrylazo III in conjunction with pulsed photolysis of DM-nitrophen-Ca2+ enabled an upper limit of the half-time of release of Ca2+ to be established of ca. 180 ps (the rate of association of Ca2+ with the dye was probably rate determining). The rate of Ca2+ photorelease may, however, be faster than this. Thus, the DM-nitrophen-Ca2+ complex releases Ca2+ on photolysis sufficiently rapidly for the study of many Ca2+-dependent physiological processes with improved kinetic resolution over conventional mixing methods.Many physiological processes take place in time periods of short duration (microsecond to millisecond time domain). Muscle contraction, synaptic transmission, hormone secretion, etc., are some of the processes which respond to brief, localized fluctuations in various effector molecules. In many situations, kinetic resolution of the process is limited by diffusional mixing