b'Protein sample preparation Because of the heterogeneity of proteins, there is no one method or reagent that is optimal for general protein isolation and purification. The first step in protein analysis is cellular extraction. Following lysis, and depending on the next step in the workflow, the protein extract may require further cleanup, using techniques such as dialysis, desalting, or concentration. After any cleanup procedure, the amount of protein in the sample should be determined using any one of numerous protein assays. Protein extraction reagents Protein biology workowand kits14Cloning andDetergents16 proteinexpressionProtease andphosphatase inhibitors17 CrudeproteinProtein ProteinSlide-A-Lyzer dialysis sample Protein gelproducts18 preparation purication electrophoresisZeba desaltingproducts20 ImmunoassaysWesternProtein concentrators22 blottingProtein quantitationproducts23Ordering information26 Protein bioconjugation,crosslinking, Mass Cryo-EM sampleand modication spectrometry preparation12 Protein sample preparation thermofisher.com/proteinbiology'