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pH‐regulated formation of side products in the reductive amination approach for differential labeling of peptides in relative quantitative experiments
Author(s) -
Mortera Stefano Levi,
Dioni Ilaria,
Greco Viviana,
Neri Cristina,
Rovero Paolo,
Urbani Andrea
Publication year - 2014
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.201300484
Subject(s) - reductive amination , chemistry , formaldehyde , acetaldehyde , reagent , side chain , adduct , combinatorial chemistry , amination , organic chemistry , ethanol , catalysis , polymer
Among the most common stable‐isotope labeling strategies, the reaction of formaldehyde with peptides in the presence of N a CNBH 3 features many attractive aspects that are conducive to its employment in quantitation experiments in proteomics. Reductive amination, with formaldehyde and d(2)‐formaldehyde, is reported to be a fast, easy, and specific reaction, undoubtedly inexpensive if compared with commercially available kits for differential isotope coding. Acetaldehyde and d(4)‐acetaldehyde could be employed as well without a substantial increase in terms of cost, and should provide a wider spacing between the differentially tagged peptides in the mass spectrum. Nevertheless, only a single paper reports about a diethylation approach for quantitation. We undertook a systematic analytical investigation on the reductive amination of some standard peptides pointing out the occasional occurrence of side reactions in dependence of pH or reagents order of addition, particularly observing the formation of cyclic adducts ascribable to rearrangements involving the generated S chiff‐base and all the nucleophilic sites of its chemical environment. We also tried to evaluate how much this side‐products amount may impair isotope coded relative quantitation.