The stability of cysteine and cystine during acid hydrolysis of proteins and peptides.
The stability of cysteine and cystine during acid hydrolysis of proteins and peptides.
复制标题
蛋白质和肽酸水解过程中半胱氨酸和胱氨酸的稳定性。
DOI：
10.1016/s0021-9258(18)63428-3
复制
发表时间：
1970
期刊：
影响因子：
--
通讯作者：
T. Liu
中科院分区：
文献类型：
--
作者：
A. Inglis;T. Liu
胱氨酸和半胱氨酸的溶液先用二硫苏糖醇处理，再用连四硫酸钠处理，可得到定量的S-磺基半胱氨酸。该反应已被应用于蛋白质水解产物，所得S-磺基半胱氨酸已在氨基酸分析仪上用离子交换色谱法测定。使用核糖核酸酶和还原型谷胱甘肽，该方法给出了蛋白质或肽的胱氨酸或半胱氨酸含量的准确值。当色氨酸也存在时，向用于水解的6 nHCl中加入少量连四硫酸钠通常被证明是可取的;连四硫酸钠的功能似乎是与吲哚核反应。通过这种修改，该程序已经给出了链球菌蛋白酶、溶菌酶和羊毛的半胱氨酸加胱氨酸含量的精确结果。结果表明，就其一级结构而言，半胱氨酸和胱氨酸在这些条件下的酸水解过程中不被破坏;用二硫苏糖醇和连四硫酸盐处理可将水解产物中任何改变形式的氨基酸转化为S-磺基半胱氨酸，并允许以该衍生物的形式定量回收。这种测定蛋白质中半胱氨酸含量的方法为测定半胱氨酸或S-羧甲基半胱氨酸等氨基酸提供了一种替代方法。该处理不影响水解产物中其他氨基酸的回收率，但酪氨酸可能除外。
When solutions of cystine and cysteine are treated with dithiothreitol and then with sodium tetrathionate, quantitative yields ofS-sulfocysteine can be obtained. This reaction has been applied to protein hydrolysates and the resultingS-sulfocysteine has been determined by ion exchange chromatography on an amino acid analyzer. With ribonuclease and reduced glutathione this procedure has given accurate values for the cystine or cysteine content of the protein or peptide. When tryptophan is also present, the addition of a small amount of sodium tetrathionate to the 6nHCl used for the hydrolysis has usually proved to be desirable; the function of the tetrathionate appears to be to react with the indole nucleus. With this modification, the procedure has given precise results for the cysteine plus cystine contents of streptococcal proteinase, lysozyme, and wool. The results indicate that, in terms of their primary structures, cysteine and cystine are not destroyed during acid hydrolysis under these conditions; treatment with dithiothreitol and tetrathionate serves to convert any altered forms of the amino acids in the hydrolysates toS-sulfocysteine and to permit quantitative recovery in the form of this derivative. This method for determining the half-cystine content of proteins provides an alternative to the determinations of the amino acids as cysteic acid orS-carboxymethylcysteine. The treatment does not affect the recoveries of other amino acids in the hydrolysate, with the possible exception of tyrosine.