b'Mass spectrometry Mass spectrometry (mass spec or MS) has become a method of choice for protein analysis. The accuracy, sensitivity, and flexibility of MS instruments have enabled new applications in biological research, biopharmaceutical characterization, and diagnostic detection. MS can identify and quantify known and unknown compounds by revealing their structural and chemical properties. With its many forms of ionization and measurement, MS enables the analysis of samples ranging in mass from 50 to 300,000 Da, in attomole through nanomole quantities. Proper sample preparation and chromatography, as well as the right instrumentation and software, are critical components of successful MS-based proteomic analysis.Tandem Mass Tag Protein biology workow(TMT and TMTpro) systems90Cloning andSureQuant assays proteinand standards92 expressionHeavyPeptide and CrudeLightPeptide AQUA proteincustom standards93 Protein Protein Proteinsample purication gelpreparation electrophoresisProtein sample preparation95Instrument calibration97 ImmunoassaysWesternOrdering information99 blottingProtein bioconjugation, Mass Cryo-EM samplecrosslinking, spectrometry preparationand modicationMass spectrometry thermofisher.com/proteinbiology 87'