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The biuret reagent is made of sodium hydroxide (NaOH) and hydrated copper(II) sulfate, together with potassium sodium tartrate, [7] the latter of which is added to chelate and thus stabilize the cupric ions. The reaction of the cupric ions with the nitrogen atoms involved in peptide bonds leads to the displacement of the peptide hydrogen atoms ...
The biuret test is a chemical test for proteins and polypeptides. It is based on the biuret reagent, a blue solution that turns violet upon contact with proteins, or any substance with peptide bonds. The test and reagent do not actually contain biuret; they are so named because both biuret and proteins have the same response to the test.
BCA protein assay in a 96 well plate. The bicinchoninic acid assay (BCA assay), also known as the Smith assay, after its inventor, Paul K. Smith at the Pierce Chemical Company, [1] now part of Thermo Fisher Scientific, is a biochemical assay for determining the total concentration of protein in a solution (0.5 μg/mL to 1.5 mg/mL), similar to Lowry protein assay, Bradford protein assay or ...
The method combines the reactions of copper ions with the peptide bonds under alkaline conditions (the Biuret test) with the oxidation of aromatic protein residues. The Lowry method is based on the reaction of Cu +, produced by the oxidation of peptide bonds, with Folin–Ciocalteu reagent (a mixture of phosphotungstic acid and phosphomolybdic acid in the Folin–Ciocalteu reaction).
The traditional method for measuring total protein uses the biuret reagent, but other chemical methods such as dye-binding and refractometry are now available. The measurement is usually performed on automated analysers along with other laboratory tests. [citation needed]
Copper(II) sulfate is also used in the Biuret reagent to test for proteins. Copper sulfate is used to test blood for anemia . The blood is dropped into a solution of copper sulfate of known specific gravity —blood with sufficient hemoglobin sinks rapidly due to its density, whereas blood which sinks slowly or not at all has an insufficient ...
Lowry assay is similar to biuret assays, but it uses Folin reagent which is more accurate for quantification. Folin reagent is stable at only acidic conditions and the method is susceptible to skewing results depending on how much tryptophan and tyrosine is present in the examined protein. [12]
The Biuret assay utilizes a biuret reagent which turns purple in the presence of proteins due to the chelation of copper salts in an alkaline solution. [4] Enzyme linked immunoassays use enzyme-complexed-antibodies to detect antigens. Binding of the antibody is often inferred from the color change of reagents such as TMB.