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Biuret test. In chemistry, the biuret test (IPA: / ˌbaɪjəˈrɛt /, / ˈbaɪjəˌrɛt / [1]), also known as Piotrowski's test, is a chemical test used for detecting the presence of at least two peptide bonds in a molecule. In the presence of peptides, a copper (II) ion forms mauve -colored coordination complexes in an alkaline solution.
Biuret (/ ˈbjurɛt / BYUR-ret) is a chemical compound with the chemical formula HN (CONH2)2. It is a white solid that is soluble in hot water. A variety of organic derivatives are known. The term "biuret" also describes a family of organic compounds with the chemical formula R1R2N−C (=O)−N (R3)−C (=O)−NR4R5, where R1, R2, R3, R4 and R5 ...
Benedict's reagent (often called Benedict's qualitative solution or Benedict's solution) is a chemical reagent and complex mixture of sodium carbonate, sodium citrate, and copper (II) sulfate pentahydrate. [1] It is often used in place of Fehling's solution to detect the presence of reducing sugars. The presence of other reducing substances ...
The Bradford protein assay (also known as the Coomassie protein assay) was developed by Marion M. Bradford in 1976. [1] It is a quick and accurate [2] spectroscopic analytical procedure used to measure the concentration of protein in a solution. The reaction is dependent on the amino acid composition of the measured proteins.
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 well-established test is a positive control since we already know that the answer to the question (whether the test works) is yes. Similarly, in an enzyme assay to measure the amount of an enzyme in a set of extracts, a positive control would be an assay containing a known quantity of the purified enzyme (while a negative control would ...
Protein precipitation. Protein precipitation is widely used in downstream processing of biological products in order to concentrate proteins and purify them from various contaminants. For example, in the biotechnology industry protein precipitation is used to eliminate contaminants commonly contained in blood. [1]
Millon's reagent is an analytical reagent used to detect the presence of soluble proteins. A few drops of the reagent are added to the test solution, which is then heated gently. A reddish-brown coloration or precipitate indicates the presence of tyrosine residue which occur in nearly all proteins. [1] The test was developed by the French ...