Structure and Stabilities of Solution and Gas Phase Protein Complexes

Area of Science:

• Biophysical Chemistry
• Mass Spectrometry
• Structural Biology

Background:

• Collision-induced unfolding (CIU) and variable-temperature electrospray ionization (vT-ESI) are key techniques for studying gas-phase protein ions.
• Understanding the persistence of solution structures in the gas phase is crucial for interpreting mass spectrometry data.

Purpose of the Study:

• To investigate the stability and structural retention of proteins and protein complexes in the gas phase after electrospray ionization.
• To explore the influence of water removal and cofactors on protein structure and stability using CIU and vT-ESI.
• To address fundamental questions about how long and to what extent solution structures are maintained without solvent.

Main Methods:

• Employing variable-temperature electrospray ionization (vT-ESI) coupled with ion mobility-mass spectrometry (IM-MS).
• Utilizing collision-induced unfolding (CIU) to probe gas-phase ion stability.
• Analyzing apo- and metalated-metallothionein-2A (MT) and transthyretin (TTR) proteoforms.

Main Results:

• CIU and vT-ESI provide complementary data on the stability of gas-phase versus solution-phase ions.
• The study examined distinct features of CIU and TIU across different protein complexes, including MT and TTR.
• Results highlight the significant effects of water and metal ions on protein structure and stability.

Conclusions:

• CIU and vT-ESI are powerful tools for probing the energy landscape of native proteins.
• The findings shed light on the structural dynamics and stability of proteins and protein complexes in the transition from solution to gas phase.
• This work advances our understanding of how solution structures are retained in the absence of solvent.