The study of covalent modification of peptide anions in the gas phase via ion/ion reactions in a mass spectrometer
Abstract
Carbodiimides are known to mediate condensation between amines and carboxylic acids to form amides. To covalently modify multiply charged peptide anions, DGAILDGAILD, GAILDGAILR, and GNRDADA have been reacted with Ncyclohexyl- N’-(2-morpholinoethyl)carbodiimide methyl-p-toluenesulfonate (CMCT) via gas phase ion/ion reactions in a triple quadrupole mass spectrometer. The resulting product was a complex formation between the reagent and the peptides which could be an electrostatic attachment due to the fixed charge site on the reagent or a covalent modification. These peptides were also reacted with 1-(3-dimehtylaminopropyl)-3-ethylcarbodiimide methoiodide (DEC) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) producing a complex formation and proton transfer reaction, respectively. A reagent derivative of CMCT was synthesized to eliminate the carbodiimide functionality and the resulting compound, 1-cyclohexyl-3-(2-morpholinyl-(4)-ethyl)ureylene metho-ptoluenesulfonate (CMU), was subjected to ion/ion reaction with peptides. The complex formed from the reaction showed the same fragment loss as the reaction with CMCT.
Degree
M.S.
Advisors
McLuckey, Purdue University.
Subject Area
Analytical chemistry
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