Thermal dissociation and H/D exchange of streptavidin tetramers at atmospheric pressure

Abstract

We present an investigation of the thermal dissociation of the gas phase, non-covalent streptavidin tetramer ion. Using an extended desolvating capillary, it was observed that this complex fragments at an activation energy around 75kJ/mole. The fragmentation occurs via charge migration and the ejection of a single monomer that carries half the total charge. Temperature increases result in intensive supermetallization by sodium ions and, eventually, in thermal dissociation. Using the in-ESI source H/D exchange approach, we observed that deuterium scrambling during the dissociation is relatively low. To better understand the charged droplets dynamics, we performed accurate computer simulations of airflow inside the desolvating capillary, including calculating the gas velocity, temperature and pressure distributions.