Two-dimensional decomposition of H-D exchange mass spectra of multicharged ions of biopolymers and their separation into components with independent H-D substitutions

The work is aimed at developing a numerical method for analysing mass spectra of deutero-substituted multicharged ions of biopolymers to determine contributions of components presumably corresponding to different biomolecule conformations. The two-dimensional decomposition of the H-D exchange mass spectra of two, three and four charged apamin ions with their separation suggests that the reaction of apamin ions with ND₃ molecules in the gas phase reveals hypothetically three different structural modifications of apamin ions. Usually for H-D exchange mass spectra, the presence of many resolvable protein structures was determined from measured distributions of peak intensities of ions with the same charge state. The method is new and has no published analogues. Graphical abstract.

Two possible improvements for mass spectrometry analysis of intact biomolecules

The goals of our study were to investigate abilities of two approaches to eliminate possible errors in electrospray mass spectrometry measurements of biomolecules. Passing of a relatively dense supersonic gas jet through ionization region followed by its hitting the spray of the analyzed solution in low vacuum may be effective to keep an initial biomolecule structure in solution. Provided that retention of charge carriers for some sites in the biomolecule cannot be changed noticeably in electrospray ion source, decomposition and separation of charge-state distributions of electrosprayed ions may give additional information about native structure of biomolecules in solution.