The isoelectric point of a standard gelatin preparation
The isoelectric point of a standard gelatin preparation
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DOI：
10.1085/jgp.14.6.685
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发表时间：
1931-07-01
影响因子：
3.8
通讯作者：
Hitchcock, DI
中科院分区：
文献类型：
--
作者：
Hitchcock, DI
研究了两个标准明胶样品，都是根据公布的规范制备的，并从扩散电解质中洗净。通过4种方法测定，该材料的等电点接近pH值4.85。(1)随着明胶浓度的增加，明胶水溶液的pH值接近极限4.86[正负]0.01。(2)仅在pH为4.85[正负]0.01时，明胶的加入对醋酸缓冲液的pH值没有影响。这就给出了索伦森等离子点，也就是只对氢离子和羟基离子的等电点。(3)用稀HC1或NaOH或稀乙酸缓冲液制成的凝胶在pH值为4.85（正负）0.03时表现出最大的浊度。(4)在醋酸缓冲液中配制的0.1%明胶溶液中，极稀的胶体悬浮液只有在pH值为4.80[正负]0.01时才显示出零速度。没有证据表明明胶在广泛分离的pH值下有2个等电点。
Two samples of a standard gelatin were studied, both prepared according to published specifications and washed free from diffusible electrolytes. The isoelectric point of this material, determined in 4 ways, was close to pH 4.85. (1) The pH values of solutions of gelatin in water approached the limit 4.86 [plus or minus] 0.01 as the concentration of gelatin was increased. (2) The pH values of acetate buffers were unchanged by the addition of gelatin only at pH 4.85 [plus or minus]0.01. This gives the isoionic point of S0rensen, which is the isoelectric point with respect only to hydrogen and hydroxyl ions. (3) Gels of this gelatin made up in dilute HC1 or NaOH, or in dilute acetate buffers, exhibited maximum turbidity at pH 4.85 [plus or minus] 0.03. (4) Very dilute suspensions of collodion particles in 0.1 per cent gelatin solutions made up in acetate buffers showed zero velocity in cataphoresis experiments only at pH 4.80 [plus or minus] 0.01. No evidence was found for the assumption that gelatin has 2 isoelectric points at widely separated pH values.