Electrostatic interactions are one of the main factors influencing biomolecular conformation. The formation of noncovalent complexes by electrostatic interactions is governed by certain amino acid residues and post-translational modifications. It has been demonstrated that adjacent arginine forms noncovalent complex with phosphate; however, histidine noncovalent complexes have rarely been investigated. In the present work, we compare the interaction between basic epitopes (NLRRITRVN, SHHGLHSTPD) and diverse acidic and aromatic-rich peptides using both MALDI and ESI Mass spectrometry. We show that adjacent histidines can also form stable noncovalent bonds and that those bonds are probably formed by a salt bridge between the phosphate or the acid residues and the histidines. However, noncovalent complexes with the arginine epitopes form more readily and are stronger than those with histidine-containing epitopes.
Histidine, the less interactive cousin of arginine
