Improving the reliability of mass spectrometry measurements of peptide-zinc(II) binding constants

Abstract Thorough investigation of the many metal complexes of biological importance is highly dependent on the analytical techniques used to detect them. Nanoflow Electrospray Ionization Mass Spectrometry can be used to accurately measure peptide-zinc (II) binding constants if appropriate ionization source hardware is utilized. Binding constants for model systems have been determined with a mass spectrometer equipped with a glass nanoflow ESI emitter and compared to published results determined via other analytical methods, including isothermal calorimetry and fluorescence spectroscopy. Binding (or formation) constants of 3.6 (±0.9) × 10 4  M −1 and 6.7 (±0.4) × 10 4  M −1 were determined for the (1–16) and (1–28) β-Amyloid fragments, respectively, in reasonable agreement with published values. These results highlight the important role mass spectrometry can play in the continued use of a slate of analytical techniques for the characterization of metal-binding peptides and proteins.