Brademan et al unveiled the Interactive Peptide Spectral Annotator (IPSA), in a recent issue of Molecular and Cellular Proteomics.
The IPSA is an interactive and easily-accessible web-based annotator that can be used to conceptualize and characterize peptides with mass spectra. This tool, which can visualize peptides collected from different experimental and instrumental sources, has a variety of purposes including creating figures for publication, annotating spectra for negative-mode ionization and the like.
The IPSA can be accessed through this link:
http://www.interactivepeptidespectralannotator.com