Covalent modification of gaseous peptide ions with N-hydroxysuccinimide ester reagent ions.
Covalent modification of primary amine groups in multiply protonated or deprotonated polypeptides in the gas phase via ion/ion reactions is demonstrated using N-hydroxysuccinimide (NHS) esters as the modifying reagents. During the ion/ion reaction, the peptide analyte ions and the NHS or sulfo-NHS based reagent form a long-lived complex, which is a prerequisite for the covalent modification chemistry to occur. Ion activation of the peptide-reagent complex results in a neutral NHS or sulfo-NHS molecule loss, which is a characteristic signature of covalent modification. As the NHS or sulfo-NHS group leaves, an amide bond is formed between a free, unprotonated, primary amine group of a lysine side chain in the peptide and the carboxyl group in the reagent. Subsequent activation of the NHS or sulfo-NHS loss product ions results in sequence informative fragment ions containing the modification. The N-terminus primary amine group does not make a significant contribution to the modification process; this behavior has also been observed in solution phase reactions. The ability to covalently modify primary amine groups in the gas phase with N-hydroxysuccinimide reagents opens up the possibility of attaching a wide range of chemical groups to gaseous peptides and proteins and also for selectively modifying other analytes containing free primary amine groups.
Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, USA.
Marija
M
Mentinova
Scott A
SA
McLuckey
D000595:Amino Acid Sequence; D001622:Betaine / Q000031:analogs & derivatives* / Q000737:chemistry; D002331:Carnitine / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D009842:Oligopeptides / Q000737:chemistry*; D011522:Protons; D013388:Succinimides / Q000737:chemistry*
D005740:Gases; D007477:Ions; D009842:Oligopeptides; D011522:Protons; D013388:Succinimides; D001622:Betaine; C002889:gamma-butyrobetaine; C001426:N-hydroxysuccinimide; D002331:Carnitine