U-2012: An improved Lowry protein assay, insensitive to sample color, offering reagent stability and enhanced sensitivity

作者：Upreti Girish C^*; Wang Yanming; Finn Alona; Sharrock Abigail; Feisst Nicholas; Davy Marcus; Jordan Robert B

来源：Biotechniques, 2012, 52(3): 159-+.

DOI：10.2144/000113818

• Protein assay
• colorimetric
• color interference
• reagent stability
• enhanced sensitivity

Traditional colorimetric protein assays such as Biuret, Lowry, and modified Lowry (U-1988) are unsuitable for colored biological samples. Here we describe an improved Lowry protein assay (U-2012), which utilizes stable reagents and offers enhanced sensitivity over the U-1988 assay. U-2012 circumvents interference from colored pigments and other substances (for example sugars) bound to perchloric acid (P CA) precipitated proteins by hydrogen peroxide (H2O2) induced oxidation at 50 C. Unused hydrogen peroxide is neutralized with sodium pyruvate before protein estimation for a stable end color. The U-2012 assay is carried out on the PCA precipitated protein pellet after neutralization (with Na2CO3 plus NaOH), solubilization (in Triton-NaCl), decolorization (by H2O2) and pyruvate treatment. Protein contents in red wine and homogenates of beetroot and blueberry are calculated from standard curves established for various proteins and generated using a rectangular hyperbola with parameters estimated with Microsoft Excel%26apos;s Solver add-in. The U-2012 protein assay represents an improvement over U-1988 and gives a more accurate estimation of protein content.

• 出版日期2012-3