Trapping carbon dioxide on Arabidopsis proteome

Carbon dioxide is vital to the chemistry of life processes including including metabolism, cellular homeostasis, and pathogenesis. CO2 forms carbamates on the neutral N-terminal a-amino- and lysine e-amino-groups that regulate the activities of ribulose 1,5-bisphosphate carboxylase/oxygenase and haemoglobin, however, very few protein other carbamates are known. Tools for the systematic identification of protein carbamylation sites have not been developed owing to the reversibility of carbamate formation, and in consequence carbamylation is typically overlooked. Here we demonstrate methods to identify protein carbamates using triethyloxonium ions to covalently trap CO2 on proteins for proteomic analysis. Our method delivers evidence to support the hypothesis that carbamylation is widespread in biology, and understanding its role should significantly advance our understanding of cellular CO2 interactions.