SearchXLinks. A Program for the Identification of Disulfide Bonds in Proteins from Mass Spectra

We present the computer program SearchXLinks that analyzes mass spectra with the aim of identifying disulfide bonds and other modifications in proteins of known amino acid sequence. Disulfide bonds can be intra- or intermolecular. To decrease the number of false positives, the analysis of in-source decay and tandem mass spectra are coupled into the program. The steps taken during a SearchXLinks run are outlined, and the computational costs are discussed. The application of the program is illustrated by the analysis of data from recent studies on bovine ribonuclease A and bovine serum albumin. The software can be used free of charge on the Internet at http://www.searchxlinks.de.