Manneberg M, Lahm H W, Fountoulakis M
F. Hoffmann-LaRoche Ltd., Basel, Switzerland.
Anal Biochem. 1995 Jan 1;224(1):122-7. doi: 10.1006/abio.1995.1016.
Sodium azide is widely used as bacteriostatic agent during downstream processing of proteins. Amino acid composition analysis of protein samples, subjected to hydrolysis with hydrochloric acid in a buffer containing sodium azide, revealed the presence of cysteic acid, methionine sulfoxide, and methionine sulfone in addition to the expected reaction products. Hydrolysis with methanesulfonic acid in the presence of sodium azide resulted in detection of only methionine sulfoxide in addition to the expected products. When the proteins were hydrolyzed in a buffer containing no sodium azide or after its removal by dialysis, no oxidation products were detected (except for minor amounts of methionine sulfoxide). The generation of the particular oxidation products was affected by the concentration of sodium azide in the protein solution. Therefore, presence of sodium azide in protein samples intended for amino acid composition analysis may lead to wrong conclusions concerning oxidation of cysteine and methionine residues.
叠氮化钠在蛋白质下游加工过程中被广泛用作抑菌剂。在含有叠氮化钠的缓冲液中用盐酸水解蛋白质样品后进行氨基酸组成分析，结果显示除了预期的反应产物外，还存在半胱磺酸、甲硫氨酸亚砜和甲砜基甲硫氨酸。在叠氮化钠存在的情况下用甲磺酸水解，除了预期产物外，仅检测到甲硫氨酸亚砜。当蛋白质在不含叠氮化钠的缓冲液中水解或通过透析去除叠氮化钠后水解时，未检测到氧化产物（除了少量甲硫氨酸亚砜）。特定氧化产物的生成受蛋白质溶液中叠氮化钠浓度的影响。因此，用于氨基酸组成分析的蛋白质样品中存在叠氮化钠可能会导致关于半胱氨酸和甲硫氨酸残基氧化的错误结论。
