Identification of degradation products formed during performic oxidation of peptides and proteins by high-performance liquid chromatography with matrix-assisted laser desorption/ionization and tandem mass spectrometry.
Oxidation of proteins with performic acid is extensively used to cleave disulfide bonds. Due to its efficiency and many other advantages it deserves more attention especially in proteomics as a method for sample treatment. However, some unwanted degradations can occur during performic oxidation. In this work the degradation products during performic oxidation of two peptides and bovine serum albumin as model substrates were explored by coupling high-performance liquid chromatography (HPLC) to matrix-assisted laser desorption/ionization tandem mass spectrometry (MALDI-TOF/TOFMS). In addition to well-known modifications such as oxidation of tryptophan and oxidation and chlorination of tyrosine, novel degradation products including nonspecific cleavage after asparagine or tryptophan, formylation of lysine, and beta-elimination of cysteine, were observed. Although almost all of these modification/degradation products except oxidation products of tryptophan were formed at sub-stoichiometric levels, they can cause confusion as a result of the sensitivity of mass spectrometry in analysis of the oxidized samples, especially in proteomics research. The results presented here will facilitate the interpretation of analytical data for performate-oxidized samples, and help to select appropriate methods for each unique sample.
Dai
Jingquan
J
Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850, China.
Zhang
Yangjun
Y
Wang
Jinglan
J
Li
Xiaohai
X
Lu
Zhuang
Z
Cai
Yun
Y
Qian
Xiaohong
X
D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D005561:Formates / Q000737:chemistry*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D012680:Sensitivity and Specificity; D012710:Serum Albumin, Bovine; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D005561:Formates; D010455:Peptides; D011506:Proteins; C008817:peroxyformic acid; D012710:Serum Albumin, Bovine