How does biuret solution work

Long polypeptides proteins have many peptide bonds and produce a positive reaction to the reagent. The violet color is a positive test for the presence of protein, and the intensity of the color is proportional to the number of peptide bonds in the solution. Proteins are Polymers of Amino Acids Proteins provide much of the structural and functional capacity of cells. Three amino acids bound into a tripeptide. How Amino Acids Interact with Each Other and the Environment Use the following simulation to test how a polypeptide chain with fold based on the type of solution it is in and the composition of the amino acids.

Diversity of Proteins Learn more about the complexity of protein structures at the Protein Data Bank. Biuret Test Examine the table below. From: biuret test in A Dictionary of Biology ». Subjects: Science and technology — Chemistry. View all related items in Oxford Reference ». Search for: 'biuret test' in Oxford Reference ». All Rights Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single entry from a reference work in OR for personal use for details see Privacy Policy and Legal Notice.

Oxford Reference. Publications Pages Publications Pages. Recently viewed 0 Save Search. That is because proteins are made up of polypeptide s, which in turn, are made of amino acid s joined by peptide bonds. The longer the polypeptide chain is, the more peptide bonds there are, and therefore, the more intense the violet colour will be when biuret test is applied.

It also follows that a pale violet or pinkish colour indicates shorter polypeptide chains or fewer peptide bond s. A negative result lack of violet colour formation may mean lack of protein , or the presence of free amino acids without peptide bonds.

The test, however, gives positive result to any compound containing two carbonyl groups attached to a nitrogen or carbon atom. Thus, it may not be completely protein -specific. Performing other protein tests may be necessary.

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