The goal of the Human Proteome Project is to elucidate all of the proteins in the human body. Tandem mass spectrometry is a cost effective and reliable approach for determining which proteins are present in solution. It has been shown that the addition of Cr(III) to peptide solutions being electrosprayed has great promise for expanding the range of acidic and basic peptides that can be studied by positive ion mass spectrometry and also for increasing the sensitivity and accuracy of the analysis. In addition to Cr(III), experimentally, Fe(III) has been shown to weakly increase this effect and Al(III) has been shown to have no effect. Computational electronic structure calculations are being used to study the interactions of these trivalent metals with neutral and anionic amino acids. The calculations are done using density functional theory with the B3LYP exchange-correlation functional. Both the C-terminus and either the N-terminus or some acidic or basic group are involved in the mechanism of enhanced protonation. Aliphatic and hydroxylic amino acids, in their neutral state have no additional sites for protonation. Arginine, histidine, lysine, glutamic acid, asparagine, and glutamine neutral species favor protonation. Diprotonated species were also studied to better understand the mechanism for the enhancement of such protonation states by Cr(III), Fe(III), and Al(III) in aqueous solution.

Enhanced ionization of peptides using trivalent metals: Developing the basis for proteomics studies

255th National Meeting (2018)

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