KB03004 | Lowry Protein Quantification Assay Kit

Lowry Protein Quantification Assay is based on Lowry method, first described in 1951. The method relies on two different reactions. The first is the formation of a copper ion complex with amide bonds, forming reduced copper in alkaline solutions. This is called a Biuret chromophore and is commonly stabilized by the addition of tartrate. The second reaction is the reduction of Folin-Ciocalteu reagent (phosphomolybdate and phosphotungstate), primarily by the reduced copper-amide bond complex as well as by tyrosine, tryptophan, histidine, cysteine, and cysteine residues in the protein. The monovalent copper ion catalyzes the latter reaction.
The reduced Folin-Ciocalteu reagent is blue and thus detectable with a spectrophotometer in the range of 500 to 750 nm. The Biuret reaction itself is not very sensitive. Using the Folin-Ciocalteu reagent to detect reduced copper makes the Lowry assay nearly 100 times more sensitive than the Biuret reaction alone.