Observation of Non-Covalent Complexes of Citrate Synthase and NADH by ESI/TOF Mass Spectrometry

Electrospray ionization/time-of-flight (ESI/TOF) mass spectrometry is a powerful tool for the study of large noncovalent complexes. The gentle nature of the electrospray technique preserves higher order structures, allowing their accurate mass measurement by time-of-flight mass spectrometry over a wide m/z range. Here we demonstrate the application of ESI/TOF MS in the detection of noncovalent complexes and quaternary structural changes as a result of ligand binding to an allosteric enzyme.