Competitive LC-MS/MS assay to investigate protein metalation dynamics

Area of Science:

• Chemical Biology
• Medicinal Chemistry
• Biochemistry

Background:

• Metallodrugs show promise but their reactivity and toxicity are often generalized due to knowledge gaps in biospeciation.
• Understanding metallodrug interactions with biomolecules is crucial for their pharmaceutical development.

Purpose of the Study:

• To develop a rapid assay for determining metallodrug-protein interactions in competitive biological environments.
• To investigate the time-dependent reactivity and selectivity of platinum(II), ruthenium(II), and iridium(III) metallodrugs with protein mixtures.

Main Methods:

• A rapid and competitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay was developed.
• Time-dependent reactivity of metallodrugs with an equimolar protein mixture was analyzed.
• Online top-down fragmentation was used for binding site localization.

Main Results:

• The assay revealed metal-dependent selectivity in adduct formation and deactivation by nucleophiles like glutathione (GSH).
• Platinum(II) derivatives showed high reactivity with sulfur donors, while ruthenium(II) compounds preferred N-donor coordination (histidine residues).
• Iridium(III) compounds formed adducts with GSH, indicating rapid transformation via redox activity.

Conclusions:

• Metallodrug reactivity is more selective in competitive biological settings than previously assumed.
• Intracellular selectivity of metallodrugs can be chemically tuned, guiding future metallodrug design.
• The developed assay can be expanded to mimic physiological environments for more accurate metallodrug design.