The total nitrogen content of egg albumin and other proteins
The total nitrogen content of egg albumin and other proteins
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DOI：
10.1042/bj0370354
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发表时间：
1943-01-01
影响因子：
4.1
通讯作者：
Williams, EF
中科院分区：
文献类型：
--
作者：
Chibnall, AC;Rees, MW;Williams, EF
近几年来。许多蛋白质化学家一直在采用凯氏定氮法估算蛋白质和蛋白质水解产物中的 N，但结果较低；如果使用微观方法，则尤其如此。举例来说，蛋白质氮含量的记录值明显低于奥斯本和索伦森等早期权威机构获得的值。这些低值有两个原因： (1) 消化时间太短：对于蛋白质和蛋白质水解产物，需要继续加热 8 小时。或在摘要清除后更多。 (2) 某些蛋白质（例如卵白蛋白、胃蛋白酶和胰岛素）在无水时具有很强的吸湿性，如果不采取特殊预防措施就无法进行处理；因此，只要可能，应在风干材料的单独样品上检测水分和氮含量。使用所描述的技术，获得了无水分和无灰蛋白的 N 含量的以下值：蛋清蛋白（天然的和凝固的），15.76%；麻仁蛋白，18.7%； β-乳球蛋白，15.58%；酪蛋白，15.73%；阿曼丁，18.75%；胰岛素 15.54%；马羧基-Hb（水分但非无灰），16.8%。
In recent yrs. many protein chemists have been employing a technique for the Kjeldahl estimation of N in proteins and protein hydrolysates which gives low results; this is especially true if micro-methods have been used. Instances are cited in which recorded values for the N content of proteins are significantly lower than those obtained by earlier authorities such as Osborne and Sorensen. These low values are due to 2 causes: (1) The digestion period has been too short: with proteins and protein hydrolysates it is necessary to continue the heating for 8 hr. or more after the digest has cleared. (2) Certain proteins (e.g., egg albumin, pepsin and insulin), when anhydrous, are so hygroscopic that they cannot be handled without special precautions; moisture and N contents therefore should be detd., whenever possible, on separate samples of air-dried material. Using the technique described the following values have been obtained for the N content of the moisture- and ash-free protein: egg albumin (native and coagulated), 15.76%; edestin, 18.7%; [beta]-lacto-globulin, 15.58%; casein, 15.73%; amandin, 18.75%; insulin 15.54%; horse carboxy-Hb (moisture- but not ash-free), 16.8%.