Interaction of angiotensin peptides and zinc metal ions probed by electrospray ionization mass spectrometry
- Cite this article as:
- Loo, J.A., Hu, P. & Smith, R.D. J Am Soc Mass Spectrom (1994) 5: 959. doi:10.1016/1044-0305(94)80014-6
Electrospray ionization-tandem mass spectrometry experiments were used to provide evidence regarding the sites of interactions between zinc metal ions and angiotensin peptides. The electrospray ionization mass spectra of histidine-containing human angiotensin II (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe) and angiotensin I (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe-His-Leu) in the presence of zinc show abundant multiply charged ions for the zinc-attached peptide [M + aZn2+ +(c − 2a)H+]c+, where a = 1, 2 and c is charge. From collisionally activated dissociation experiments, with both low energy (triple quadrupole mass spectrometry) and high energy collisions (linked scan at constant B/E with a double focusing instrument) of the [M + Zn]2+ and [M + Zn + H]3+ ions for angiotensin II, a [b6 + Zn]2+ species is produced as the most abundant product ion, suggesting that the zinc interaction site is in the vicinity of the His6 residue. Additionally, tandem mass spectra from the zinc-attached ions for angiotensin I show abundant [b6 + Zn]2+ and [b9 + Zn]2+ products, providing evidence that both His6 and His9 are involved in zinc coordination.