Investigation of the structure, assembly and function of protein-nucleic acid macromolecular machines requires multidimensional molecular and structural biology approaches. We describe modifications to an Orbitrap mass spectrometer, enabling high-resolution native MS analysis of 0.8- to 2.3-MDa prokaryotic 30S, 50S and 70S ribosome particles and the 9-MDa Flock House virus. The instrument's improved mass range and sensitivity readily exposes unexpected binding of the ribosome-associated protein SRA.

Native mass spectrometry can provide insight into the structure of macromolecular biological systems. As analytes under investigation get larger and more complex, instrument capabilities need to be advanced. Herein, modifications to an Orbitrap Q Exactive Plus mass spectrometer that increase signal intensity, mass resolution, and maximum m/z measurable are described.