Nötzold H, Schlegel B, Breitfeld D, Freimuth U
Nahrung. 1977;21(8):697-704. doi: 10.1002/food.19770210807.
The alkali treatment of beta-lactoglobulin and alpha-lactalbumin results in the splitting of disulphide bonds in the protein molecules. When a 0.8-10(4) M beta-lactoglobulin solution in a 0.022 N sodium hydroxide solution (pH = 12) is heated at 90 degrees C for 30 min, 0-4 M disulphide groups, 2.2 M sulfhydryl groups and 1.8 M sulphide ions/M dimeric beta-lactoglobulin are detectable of the total of 4 M disulphide groups and 2 M sulfhydryl groups/M dimeric beta-lactoglobulin. The sulphide ions can be determined directly in the form of hydrogen sulphide or by calculating the difference between the values from the amperometric-argentometric titration and those from the method of ELLMAN (reaction with DTNB). The disulphide groups are determined with the aid of DTNB after reduction with sodium borohydride. The sulfhydryl groups obtained by reduction with sodium borohydride re-oxidize, the reaction velocity being of the second order. If the disulphide groups are reduced with sodium borohydride, the argentometric-amperometric determination of the sulfhydryl groups by means of the platinum rotating-disk electrode is disturbed by the presence of boric acid.
对β-乳球蛋白和α-乳白蛋白进行碱处理会导致蛋白质分子中的二硫键断裂。当0.8×10⁻⁴M的β-乳球蛋白溶液在0.022N的氢氧化钠溶液（pH = 12）中于90℃加热30分钟时，对于每摩尔二聚体β-乳球蛋白中总共4摩尔二硫键和2摩尔巯基而言，可检测到0 - 4摩尔二硫键基团、2.2摩尔巯基基团和1.8摩尔硫化物离子/摩尔二聚体β-乳球蛋白。硫化物离子可以以硫化氢的形式直接测定，或者通过计算安培 - 银量滴定法的值与ELLMAN法（与DTNB反应）的值之间的差值来测定。在用硼氢化钠还原后，借助DTNB测定二硫键基团。用硼氢化钠还原得到的巯基会重新氧化，反应速度为二级反应。如果用硼氢化钠还原二硫键基团，通过铂旋转圆盘电极对巯基进行银量 - 安培测定会受到硼酸存在的干扰。
