Determination of the appropriate valence of 1,4-piperazinediethanesulfonic acid (PIPES) in physiological pH.
Determination of the appropriate valence of 1,4-piperazinediethanesulfonic acid (PIPES) in physiological pH.
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测定生理 pH 值下 1,4-哌嗪二乙磺酸 (PIPES) 的适当价态。
DOI：
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发表时间：
1994
影响因子：
2
通讯作者：
H. Kawata
中科院分区：
文献类型：
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作者：
J. Hatae;N. Fujishiro;H. Kawata
用KOH滴定1，4-哌嗪二乙磺酸（PIPES）（一种两性离子缓冲液），以测量其pH和渗透压摩尔浓度。pH值和渗透压摩尔浓度的变化都表现出三个阶段，两个过渡点与pH值5.1和10.2相吻合。第二阶段在生物反应中很重要，从目前的结果来看，在20 ℃时pK 1为3.3，pK 2为6.85。渗透压曲线的斜率在第一和第三阶段中为2 mOsm/1 mM KOH添加，而在第二阶段中为1 mOsm/1 mM KOH添加。第一阶段表明通过添加KOH，+/- PIPES +/-变为-PIPES +/-。在第二阶段，额外的KOH产生-PIPES-。PIPES至少在约7.0的生理pH范围内充当二价离子。生理pH范围附近的-PIPES +/-和-PIPES-的浓度计算如下。[公式：见正文] PIPES的离子强度计算如下。[公式：见正文]
1,4-Piperazinediethanesulfonic acid (PIPES), a zwitterion buffer, was titrated with KOH to measure its pH and osmolality. Both pH and osmolality changes showed three phases, and two transition points coincided with pH 5.1 and 10.2. The second phase is important in biological reactions, and from the present results, the pK1 is 3.3 while pK2 is 6.85 at 20 degrees C. The slope of the osmolality curve was 2 mOsm per 1 mM KOH addition in the first and third phases, while it was 1 mOsm per 1 mM KOH in the second phase. The first phase indicates that +/- PIPES +/- changes to -PIPES +/- by the addition of KOH. In the second phase, additional KOH produces -PIPES-. PIPES acts as a divalent ion, at least, in the physiological pH range of around 7.0. Concentrations of -PIPES +/- and -PIPES- around the physiological pH range are calculated as follows. [formula: see text] The ionic strength of PIPES is calculated as follows. [formula: see text]