THE EFFECT OF PH ON RATE CONSTANTS, ION SELECTIVITY AND THERMODYNAMIC PROPERTIES OF FLUORESCENT CALCIUM AND MAGNESIUM INDICATORS
THE EFFECT OF PH ON RATE CONSTANTS, ION SELECTIVITY AND THERMODYNAMIC PROPERTIES OF FLUORESCENT CALCIUM AND MAGNESIUM INDICATORS
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DOI：
10.1016/0006-291x(91)91966-g
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发表时间：
1991-05-31
影响因子：
3.1
通讯作者：
BARTSCHAT, DK
中科院分区：
文献类型：
--
作者：
LATTANZIO, FA;BARTSCHAT, DK
荧光钙指示剂fluo-3，fura-2和indo-1，和荧光镁指示剂mag-fura-2（FURAPTRA）和mag-indo-1进行了评估的影响，其缔合和解离速率，离子选择性和热力学性质的pH值。钙指示剂对钙和镁的亲和力降低，钙和镁之间的歧视减少，在呋喃-2和indo-1在酸性pH值。表观解离常数的改变主要是由降低缔合率。镁指标没有显示这些变化。钙指示剂的钙络合物的热值为1-3千卡/摩尔，镁指示剂的镁络合物的热值为7-9千卡/摩尔。研究了fluo-3和Ca与镁指示剂相互作用的双指数解离速率的潜在影响。
Fluorescent calcium indicators fluo-3, fura-2 and indo-1, and fluorescent magnesium indicators mag-fura-2 (FURAPTRA) and mag-indo-1 were evaluated for the effects of pH on their association and dissociation rates, ion selectivity and thermodynamic properties. Calcium indicator affinities for Ca and Mg were reduced and the discrimination between Ca and Mg decreased in fura-2 and indo-1 at acidic pH. Alterations in apparent dissociation constants were caused primarily by reduced association rates. Magnesium indicators did not show these changes. The enthalphies of the calcium indicators' Ca complex were 1–3 kcal/mole and magnesium indicators' Mg complex were 7–9 kcal/mole. The potential effects of a biexponential dissociation rate of fluo-3 and of Ca interactions with magnesium indicators were examined.