Patent ID: 8592216
Filing Date: 2013-11-26
Classification: C07K,Y10T

Abstract:
1. A method of ionizing and fragmenting a peptide having an amide backbone and one or more carboxylic acid groups comprising the steps of: a) providing the peptide; b) reacting at least a portion of the carboxylic acid groups of the peptide with a tagging reagent having a functional group having a greater gas-phase basicity than the amide backbone of the peptide, wherein the tagging reagent has the formula: wherein, R R R wherein the tagging reagent and carboxylic acid groups react to link the functional group to the peptide to generate a labeled peptide, and wherein the functional group is not a nucleophile when the tagging reagent reacts with the carboxylic acid groups; c) ionizing the labeled peptide using electrospray ionization, thereby generating an ionized peptide, wherein the functional group of the labeled peptide increases the charge state of the ionized peptide compared to an unlabeled form of the peptide; and d) fragmenting the ionized peptide via electron transfer dissociation (ETD) or electron capture dissociation (ECD).