Biuret Test

24 Nov Biuret Test

Science tuition classes in Miracle Learning Centre are easy to understand and help you to improve in your grades. If you do not understand biology, you must definitely attend the science tuition class at Miracle Learning Centre. Let us learn about the Biuret Test in this science tuition lesson.

A student at Miracle Learning Centre has recently learnt that egg whites are very nutritious as the egg whites, also known as albumin, contain a large amount of protein necessary for proper development, and also provides the liquid medium in which the embryo develops. The student was interested to know how do scientists find out whether there are proteins inside egg whites, and asked her biology teacher at Miracle Learning Centre, Ms Lin, about it. Her Biology teacher at Miracle Learning Centre replied, “We can use a Biuret Test to find out.” But how are Biuret Tests carried out ?

Similar to pH indicators to confirm the acidity or basicity of a solution through a colour change, Biuret tests relies on a colour change to confirm the presence of peptide bonds, which are the basis for the formation of proteins. To carry out the Biuret Test, first add an equal amount of sodium hydroxide to egg whites and mix carefully. Then, add a few drops of 1% copper (II)sulfate without shaking the mixture. If the solution turns purple, it is a positive result: there are peptide bonds present in the solution. On the contrary, if the solution remains blue, it is a negative result: there are no peptide bonds present.

How does the Biuret Test work? The reagent used in the Biuret Test is a solution of copper (II)sulfate (CuSO4) and sodium hydroxide (NaOH). Sodium hydroxide works to raise the pH of the solution to alkaline levels. When peptide bonds are present in this alkaline solution, the Cu2+ions from the CuSO4 will form a coordination complex with 4 nitrogen atoms from peptide bonds. The complex of Cu2+ ions and nitrogen atoms make the colour of copper (II)sulfate solution changes from blue to purple. This colour change is dependent on the number of peptide bonds in the solution, so the more protein, the more intense the change.

Miracle Learning Centre would like to bring you more articles on science tuition concepts. We hope you have understood how a Biuret Test works. Do come to Miracle Learning Centre for more science tuition lessons to learn more about Biuret Tests.

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