Recent Advances in Supercharging of Proteins During Electrospray Ionization

Electrospray ionization (ESI) is one of the most commonly used mass spectrometry ionization techniques for biomolecules at present. Biological macromolecules such as proteins can carry multiple charges and form multiply charged ions during ESI. The formation of multiply charged protein ions can effectively reduce the mass-to-charge ratio (m/z) of the ions to be measured, expand the range of molecular weights detectable and improve the detection sensitivity, which brings more convenience to mass spectrometry analysis of biological macromolecules. Recently, several methods have been proposed to further increase the charge of protein ions during ESI, and these methods has been called supercharging of proteins. In this paper, several methods for supercharging of proteins developed recently are systematically classified and summarized, the ionization mechanism and influencing factors of these methods are reviewed, and their applications are also introduced.