蛋白检测方法

Protein concentration is commonly estimated by measuring the absorb ance at 280nm and calculating the concentration using the extinctio n coefficient of the protein.The procedure is feasible because exti nction coefficients are typically obtained using standard cuvettes with a fixed 1 cm pathlength. Extinction-based protein assays can a lso be done in microplates, but they have not been widelyused becau se of the inconvenience of compensating for variable pathlengths of samples in microplate wells. The introduction of the Molecular Devi ces’ SPECTRAmax PLUS microplate spectrophotometer marks the first time that photometric measurements made in a microplate format can be automatically normalized such that the resultant values are iden tical to those obtained with the corresponding solutions in a stand ard 1 cm pathlength cuvette. The following application note outline s the use of the pathlength correction feature “Pathcheck”, compa res absorbance results obtained in cuvettes and microplate, and giv es an example where Pathcheck is applied to column chromatographic fractions and the elution profile displayed.