Ahmed Z, Kragie L, Connor J A
Biophys J. 1980 Dec;32(3):907-20. doi: 10.1016/S0006-3495(80)85025-9.
In vitro and in situ tests have been run to characterize the reaction of the mettalochromic indicator, arsenazo III, with calcium. Job plots as well as plots of indicator absorbance vs. [Ca2+] at different indicator concentrations show a 1:1 reaction stoichiometry. Equilibrium analysis and analysis using Adair's equation are also consistent with 1:1 complexes being formed and give estimates of 34 and 45 muM for the apparent dissociation constant. In situ tests were carried out using giant neurons from Archidoris monteryensis, a marine gastropod mollusc. Dye absorbance changes were measured during voltage clamp pulses which produced a fixed calcium influx. The dependence of absorbance change on total dye concentration is consistent with the formation of a 1:1 complex of Ca with ArIII if measurements are made during the initial period of the loading pulse, less than 300 ms, although the apparent dependency changes with longer delay in measurements from the onset of the pulse.
已进行体外和原位试验来表征金属变色指示剂偶氮胂III与钙的反应。不同指示剂浓度下的乔布图以及指示剂吸光度与[Ca2+]的关系图显示反应化学计量比为1:1。平衡分析以及使用阿代尔方程的分析也与形成1:1配合物一致，并给出了表观解离常数的估计值为34和45 μM。原位试验使用了海洋腹足纲软体动物蒙特里阿氏多彩海蛞蝓的巨型神经元进行。在产生固定钙内流的电压钳脉冲期间测量染料吸光度变化。如果在加载脉冲的初始阶段（小于300毫秒）进行测量，吸光度变化对总染料浓度的依赖性与Ca与ArIII形成1:1配合物一致，尽管随着从脉冲开始测量的延迟时间延长，表观依赖性会发生变化。
