OBJECTIVETo observe the effects of different cell lysis buffers on protein quantification with Bradford method and bicinchoninic acid (BCA) method.

METHODSBradford method and BCA method were used to determine the concentration of bovine serum albumin (BSA) in different solutions (distilled water, cell lysis buffer used in two-dimensional differential in-gel electrophoresis and three kinds of cell lysis buffers used in conventional two dimensional gel electrophoresis), as well as the protein concentrations of cell lysates using these different lysis buffers. Bradford method was also applied to determine the protein concentrations of samples with repeated freeze thaw cycle, in different colorimetric cylinders, or using different standard curves from different periods.

RESULTThe protein measurements increased for 1.2 to 2 fold when different cell lysis buffers were used in Bradford method, but the measurements increased with the increased concentration of BSA (r=0.989 approximately 0.996, P<0.05). For BCA, measurement reading increased about thousands times higher, even overflowed the limits of machine. Protein measurements didn't change significantly, only showed a declined trend after repeated freeze thaw cycle, while no significant changes were found using different colorimetric cylinders or standard curves from different periods.

CONCLUSIONBradford method may be the choice of the protein quantification in proteomics. However, optimization is required for specific experimental conditions.