Methods and apparatuses for the identification and/or characterization of properties of a macromolecule based on mass spectrometry data. Specifically, described herein are methods and apparatuses for converting peptide-level data into a pseudo-intact mass spectra. Also described herein are methods and apparatuses for converting peptide-level data into a pseudo-electropherogram. The methods may be well suited for analyzing proteins and protein complexes, including estimating properties of post-translational modifications of the proteins and protein complexes. Methods may include generating a theoretical graph or spectrum based on peptide-level mass spectrometry data. In some embodiments, the theoretical graph may be a theoretical intact mass spectrum or a theoretical charge distribution spectrum.