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Use of 2,6‐Dihydroxyacetophenone for Analysis of Fragile Peptides, Disulphide Bonding and Small Proteins by Matrix‐assisted Laser Desorption/Ionization
Author(s) -
Gorman Jeffrey J.,
Ferguson Bettina L.,
Nguyen Thuong B.
Publication year - 1996
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/(sici)1097-0231(19960331)10:5<529::aid-rcm522>3.0.co;2-9
Subject(s) - chemistry , matrix assisted laser desorption/ionization , fragmentation (computing) , mass spectrometry , peptide , desorption , phosphopeptide , chromatography , small molecule , biochemistry , organic chemistry , adsorption , computer science , operating system
Several peptides were shown to undergo fragmentation during matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry to a degree which complicated their analysis using β‐cyano‐4‐hydroxycinnamic acid (CHCA) as a matrix, even at threshold laser irradiance. These peptides included synthetic peptides, peptides isolated from viral proteins and a phosphopeptide from β‐casein (residues 33–48). The excessive fragmentation occurred usually as a post‐source phenomenon; however, in‐source fragmentation was also observed. The combined effects of in‐source and post‐source fragmentation of one peptide studied led to a failure to observe the protonated molecule of this peptide in reflector mode analysis. The phosphopeptide studied exhibited a high degree of β‐elimination of phosphate. It was demonstrated that the fragility exhibited by these peptides in CHCA, including β‐elimination of phosphate from serine, was not evident with a matrix comprising 2,6‐dihydroxyacetophenone (DHAP) and di‐ammonium hydrogen citrate (DAHC). The DHAP/DAHC matrix was also adapted for direct analysis of peptides from an acidic reducing milieu containing tris(2‐carboxyethyl)phosphine. The molecular weight of equine cytochrome c was determined with a relatively high degree of accuracy (experimental M r =12360.2±1.4 Da compared to the theoretical M r =12360.09 Da) using DHAP/DAHC as a matrix for reflector mode analysis.