Thermal denaturation of some proteins and its effect on their electrospray mass spectrat

Abstract

Abstract The effects of beat on the electrospray mass spectra of eight globular proteins in solution were studied. These ranged from hardly noticeable to a dramatic shift in the mass spectrometric profile and a concomitant increase in ion abundance. This change is believed to be the result of thermal denaturation of the protein species in solution resulting in a transition from a more compact to a less compact conformation. We accounted for this transition by means of a recently proposed model based on aqueous solution acid/base equilibria. For cytochrome c , profiles calculated by means of this model agree well with experimental data. The Δ H of the denaturation reaction of cytochrome c in aqueous solution containing 0.2% acetic acid was calculated from experimental data to be 103.8 ± 9.2 kJ mol −1 , in good agreement with previous measurements.