Hayashi R, Suzuki F
Anal Biochem. 1985 Sep;149(2):521-8. doi: 10.1016/0003-2697(85)90608-6.
Methionine sulfoxide in peptides and proteins was determined by use of 3 N p-toluenesulfonic acid as a hydrolyzing agent. Samples were hydrolyzed at 110 degrees C for 22 h in an evacuated sealed tube and analyzed for amino acid content. Amino acid analysis showed that the recovery of methionine sulfoxide from a synthetic peptide and its mixture with proteins was consistently better than 90%. The recovery of all other amino acids except tryptophan was complete, and was similar to that observed after hydrolysis with 6 N HCl. The presence of carbohydrates had no effect on the yield. Thus, the present procedure can be used for general and simultaneous determination of methionine sulfoxide as well as other amino acids in proteins.
采用3N对甲苯磺酸作为水解剂测定肽和蛋白质中的甲硫氨酸亚砜。样品在抽真空的密封管中于110℃水解22小时，然后分析氨基酸含量。氨基酸分析表明，从合成肽及其与蛋白质的混合物中回收甲硫氨酸亚砜的回收率始终优于90%。除色氨酸外，所有其他氨基酸的回收均完全，且与用6N盐酸水解后观察到的情况相似。碳水化合物的存在对产率没有影响。因此，本方法可用于蛋白质中甲硫氨酸亚砜以及其他氨基酸的常规同时测定。
