Accurate determination of protein concentration is essential in the protein analysis workflow. Although there are a wide variety of protein assays available, none of the assays can be used without first considering their suitability for the application. Each assay has its own advantages and limitations and often it is necessary to obtain more than one type of protein assay for research applications.
Bradford Reagent and SingleQuant/ProtaQuant
Assay Kits are based on protein-dye binding subsequent direct detection of
the color change associated with the bound dye.
Due to its high sensitivity, easy and rapid process Bradford Reagent is especially suitable for the fast estimation of protein concentration. However, detergents in the sample will interfere with the assay.
SingleQuant/ProtaQuant Assay Kits do not only have a broad linear measurement range but are as well not disturbed by the presence of detergents like SDS, CHAPS or reducing agents like DTT.
BCA Protein Assay Macro/Micro Kits and the Lowry Kit are based
on the reduction of copper by proteins followed by a chelation building a
BCA Protein Assay Macro/Micro Kits have the advantage that they show less binding variation between different proteins than Bradford assay and are compatible with many detergents.
Despite the development of new protein quantification kits the Lowry Assay remains a sensitive, accurate and useful method for many applications, especially for determination of protein concentration after TCA precipitation due to the removal of interfering substances.
Kits based on the binding of
fluorescent dyes to proteins and the subsequent detection of the emitted
fluorescence enable a significantly higher sensitivity and more precise
determination of protein concentration.
SERVA Purple Protein Quantification Assay uses the eco-friendly fluorescent dye SERVA Purple. The assay is not only characterized by a very high sensitivity, but also by an accurate staining of hydrophobic, glyco-, phosphoproteins and peptides.