PROBING GAS PHASE PEPTIDE STRUCTURES: INSIGHT FROM SIMULATIONS MAY CONFIRM STRUCTURAL PREFERENCES IN RADICAL INDUCED TANDEM MASS SPECTROMETRY

摘要

Desolvation and ionization, as encountered in electrospray MS, drastically affect the nature and number of non-covalent interactions shaping a biomolecule's conformation. However, when intramolecular stabilizations (hydrogen bonds, salt bridges, charge solvation) are present and electrostatic repulsion is limited, gas phase ion conformations may resemble or at least retain features of their neutral solution phase analogues. The kinetics and thermodynamics of the unfolding resulting from transition to the gas phase are difficult to measure but may be evaluated by the means of computational chemistry and further correlated to gas phase measurements for example by ion mobility mass spectrometry (IMS). Radical induced tandem MS, namely ECD/ETD, have been shown to be sensitive to hydrogen bonds and possibly to gas phase structures, as we previously reported for amphipathic peptides.[1]