Chemoselective sensitivity booster for tagging a peptide, peptide conjugate, or similar reactive molecule

A chemoselective sensitivity booster for tagging a peptide or peptide conjugate for analysis of a peptide, protein, protein bioconjugate, and antibody, wherein the chemoselective sensitivity booster comprises:

• sp2 or sp3 nitrogen centers in combination with hydrophobic carbon chains linked with an electrophile or a nucleophile,
• wherein the chemoselective sensitivity booster is selected from the group consisting of
• 2,5-dioxopyrrolidin-1-yl picolinate,
• 2,5-dioxopyrrolidin-1-yl 4-(dibenzylamino)benzoate,
• 2,5-dioxopyrrolidin-1-yl 3-(benzyl(pyridin-2-ylmethyl)amino)propanoate,
• 2,5-dioxopyrrolidin-1-yl 3-(bis(pyridin-2-ylmethyl)amino)propanoate,
• 2,5-dioxopyrrolidin-1-yl 4-(4-((dibenzylamino)methyl)-1H-1,2,3-triazol-1-yl)benzoate,
• 2,5-dioxopyrrolidin-1-yl-4-((6-(1H-imidazol-1-yl)hexyl)oxy)benzoate,
• 1-(6-(4-(((2,5-dioxopyrrolidin-1-yl)oxy)carbonyl)phenoxy)hexyl)pyridin-1-ium bromide,
• 1-benzyl-3-(6-(4-(((2,5-dioxopyrrolidin-1-yl)oxy)carbonyl)phenoxy)hexyl)-1H-imidazol-3-ium bromide,
• 4-(dimethylamino)-1-(6-(4-(((2,5-dioxopyrrolidin-1-yl)oxy)carbonyl)phenoxy) hexyl)pyridin-1-ium bromide,
• N-(bis(dimethylamino)methylene)-N-butyl-6-(4-(((2,5-dioxopyrrolidin-1-yl)oxy)carbonyl)phenoxy)hexan-1-aminium bromide, and
• 6-(aminooxy)-N-(bis(dimethylamino)methylene)-N-(6-phenoxyhexyl)hexan-1-aminium bromide.