Who discovered biuret?
von Fehling
von Fehling (1812–85).
How is the name biuret derived?
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.
What is the principle of biuret test?
Principle of Biuret test: Biuret is a compound formed by heating urea to 180° C. When biuret is treated with dilute copper sulfate in alkaline condition, a purple colored compound is formed. This is the basis of biuret test widely used for identification of proteins and amino acids.
When was biuret test discovered?
1949
The biuret test developed by the author in 1949 for estimating protein content in wheat and flour has been modified to make it simpler and more accurate. Formerly, aliquots of cleared alkaline protein extracts were combined with measured amounts of the alkaline copper reagent.
How do you remove biuret from urea?
Biuret is selectively removed from urea by treating the urea in an aqueous solution at a pH above about 12.5 and a temperature between about 0.
What substance reacts with biuret?
The biuret method is based on the fact that proteins (and, as a rule, all substances containing two or more peptidic bonds) react with copper to form a colored complex whose absorption (λmax= 454 nm), in the presence of excess copper, is proportional to the amount of protein present.
What is biuret used for?
The biuret (IPA: /ˌbaɪjəˈrɛt/, /ˈbaɪjəˌrɛt/) test, also known as Piotrowski’s test, is a chemical test used for detecting the presence of peptide bonds. In the presence of peptides, a copper(II) ion forms mauve-colored coordination complexes in an alkaline solution.
Is biuret alkaline?
Biuret Method Under strongly alkaline conditions, Cu2+ ions form multivalent complexes with peptide bonds in proteins. Binding shifts the absorption spectrum of Cu2+ ions to shorter wavelengths, leading to a color change from blue to violet that has been termed the biuret reaction.
Why does protein turn purple in biuret test?
The biuret test measures peptide bonds in a sample. Recall that proteins are made up of amino acids connected together with peptide bonds. In an alkaline solution, copper II is able to form a complex with the peptide bonds. Once this complex has been formed, the solution turns from a blue color to a purple color.
What is low biuret urea?
What is a low biuret urea fertilizer? This is a kind of water soluble fertilizer with low biuret urea (46% Nitrogen) content used for nitrogen deficiency in plants. Its formula is CO(NH2)2. It contains 46% urea nitrogen. As it is soluble in water it can easily be applied by a sprinkler or via leaves.
What is biuret in urea?
Biuret is an impurity in urea fertilizer caused by a side reaction at higher temperatures during processing. It has been identified as injurious to citrus foliage and to certain germinating seeds. The earliest urea plant designs produced urea with up to five percent biuret.
Why does histidine give a positive biuret test?
It is the result of the condensation of 2 molecules of urea. The peptide bonds in Biuret give a positive result for the test hence the reagent is named so. Histidine is the only amino acid that gives Biuret test positive.