Electrospray Ionization Mass Spectrometry Applied to Study the Radical Acetylation of Amino Acids, Peptides and Proteins

Increased chemical acetylation of peptides and proteins in rats after daily ingestion of diacetyl analyzed by Nano-Lc-MS/MS

“…[ [35][36] Acetylation in both lysine and histidine residue was previously demonstrated in vitro, [10][11][12][13] which reinforces our results about acetylation in these residues.…”

“…[5,8,9] Recently, we reported that the reaction of peroxynitrite with α-dicarbonyls, namely diacetyl and methylglyoxal, in aerated phosphate buffer pH 7.4 results in the acetylation of free amino acids, peptides and proteins added to the reaction mixture. [10][11][12][13] This reaction is initiated by nucleophilic addition of peroxynitrite to the carbonyl group of the α-dicarbonyl compound yielding a peroxynitroso adduct, whose homolysis yields acetyl radicals. Dissolved molecular oxygen adds to the radical to ultimately produce acetate from diacetyl or acetate and formate from methylglyoxal.…”

“…[13] On the other hand, diacetyl/peroxynitrite-generated acetyl radicals have proven been proven to attack both the α-and ε-amino groups of free and blocked L-Lys, L-Lys-containing peptides and serum albumin. [10] These findings have raised the hypothesis that radical acetylation of proteins contributes to transacetylase-promoted post-translational protein modifications at sites where both methylglyoxal or diacetyl and peroxynitrite are present. [10][11][12][13] From these facts, the competition of chemical (induced by diacetyl) and enzymatic (occurring naturally in organisms) acetylation can be inferred, with the former process contributing to the increase of total protein acetylation.…”

Increased chemical acetylation of peptides and proteins in rats after daily ingestion of diacetyl analyzed by Nano-LC-MS/MS

“…Recently, we reported that the reaction of peroxynitrite with α-dicarbonyls, namely diacetyl and methylglyoxal, in aerated phosphate buffer pH 7.4 results in the acetylation of free amino acids, peptides and proteins added to the reaction mixture ( Alves et al, 2013 ; Massari et al, 2010 ; Massari et al, 2011 ; Tokikawa et al, 2014 ). This reaction is initiated by nucleophilic addition of peroxynitrite to the carbonyl group of the α-dicarbonyl compound yielding a peroxynitroso adduct, whose homolysis yields acetyl radicals.…”

“…Formyl radical intermediate generated by methylglyoxal/peroxynitrite was shown to add to the α-amino group of L-lysine-containing synthesized tetrapeptides ( Tokikawa et al, 2014 ). On the other hand, diacetyl/peroxynitrite-generated acetyl radicals have proven been proven to attack both the α- and ε-amino groups of free and blocked L-Lys, L-Lys-containing peptides and serum albumin ( Alves et al, 2013 ). These findings have raised the hypothesis that radical acetylation of proteins contributes to transacetylase–promoted, post-translational protein modifications at sites where both methylglyoxal or diacetyl and peroxynitrite are present ( Alves et al, 2013 ; Massari et al, 2010 ; Massari et al, 2011 ; Tokikawa et al, 2014 ).…”