b'ConcentrationPrecipitation Protein concentration and diafiltration, similar toProtein precipitation removes interfering substances by dialysis, uses a semipermeable membrane to separateselectively precipitating proteins using trichloroacetic acid macromolecules from low molecular weight compounds.(TCA) or acetone. The solution containing the interfering Unlike dialysis, which relies on passive diffusion,substance is removed, and the protein is then resolubilized concentration is achieved by forcing both liquid (buffers)in an assay-compatible buffer. Commercially available and low molecular weight solutes through the membranekits simplify sample pretreatment for protein assays. by centrifugation, where they are collected on the otherSmall molecules may be separated from large proteins side (filtrate). Macromolecules remain on the sample sidein a sample via precipitation with acetone. When used of the membrane, where they become concentrated toin combination with 96-well centrifuge filter plates, this a smaller volume (retentate). For buffer exchange, themethod is ideal for processing many samples at once.retentate is diluted to the original volume with exchange buffer and centrifuged multiple times until the desired level of exchange has been achieved. Our high-performance Thermo Scientific Pierce Protein Concentrators enable rapid sample processing with high protein recovery.Comparison of protein sample clean-up methodsTechnique DialysisDesalting Concentration Precipitation Best for Buffer exchange,Desalting, bufferSample concentration,Complete buffer desalting exchange desalting, buffer exchange replacementAdvantages Maximum flexibility inSpeed Best for low- toLow cost, good for processing volume,medium-volume samples;small volumeswide range of molecularfast compared to weight cutoffs traditional dialysis Disadvantages Slow and multipleLimited sample volumePotential protein loss Higher protein lossrounds of dialysis maycan be processed at be required a timeSample processing~224 hr ~510 min ~530 min ~5 mintimeSample volume10 L250 mL2 L4 mL 100 L100 mL Anyprocessing rangesRecommendedPurified protein Lysate or purified protein Lysate or purified protein Lysate or purified proteinsample typeRecommendedThermo ScientificThermo Scientific ZebaThermo ScientificThermo Scientific product Slide-A-LyzerSpin Desalting Columns Pierce ProteinPierce SDS-PAGE Cassettes Concentrators Sample Prep KitDownload the protein clean-up handbook to learn more39'