Mapping protein cysteine sulfonic acid modifications with specific enrichment and mass spectrometry: an integrated approach to explore the cysteine oxidation.
Oxidation of thiol proteins, which results in conversion of cysteine residues to cysteine sulfenic, sulfinic or sulfonic acids, is an important posttranslational control of protein function in cells. To facilitate the analysis of this process with MALDI-MS, we have developed a method for selective enrichment and identification of peptides containing cysteine sulfonic acid (sulfopeptides) in tryptic digests of proteins based on ionic affinity capture using polyarginine-coated nanodiamonds as high-affinity probes. The method was applied to selectively concentrate sulfopeptides from either a highly dilute solution or a complex peptide mixture in which the abundance of the sulfonated analyte is as low as 0.02%. The polyarginine-coated probes exhibit a higher affinity for peptides containing multiple sulfonic acids than peptides containing single sulfonic acid. The limit of the detection is in the femtomole range, with the MALDI-TOF mass spectrometer operating in the negative ion mode. The results show that the new approach has good specificity even in the presence of phosphopeptides. An application of this method for selective enrichment and structural identification of sulfopeptides is demonstrated with the tryptic digests of performic-acid-oxidized BSA.
Chang
Yuan-Chang
YC
Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan.
Huang
Chien-Ning
CN
Lin
Chia-Hung
CH
Chang
Huan-Cheng
HC
Wu
Chih-Che
CC
D000595:Amino Acid Sequence; D002846:Chromatography, Affinity / Q000379:methods; D003545:Cysteine / Q000737:chemistry* / Q000378:metabolism; D018130:Diamond / Q000737:chemistry; D005561:Formates; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000737:chemistry / Q000378:metabolism; D049329:Nanostructures; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D010449:Peptide Mapping / Q000379:methods*; D010455:Peptides / Q000737:chemistry; D010748:Phosphopeptides; D012680:Sensitivity and Specificity; D012710:Serum Albumin, Bovine / Q000737:chemistry / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013451:Sulfonic Acids / Q000737:chemistry* / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism
D005561:Formates; D007328:Insulin; D010446:Peptide Fragments; D010455:Peptides; D010748:Phosphopeptides; D013451:Sulfonic Acids; C008817:peroxyformic acid; C015462:polyarginine; D012710:Serum Albumin, Bovine; D018130:Diamond; D014357:Trypsin; D003545:Cysteine