Indicator s Test BIURET TEST Biuret test is a biochemical test used for detectin
ID: 280922 • Letter: I
Question
Indicator s Test BIURET TEST Biuret test is a biochemical test used for detecting the presence of peptide bonds (bond between two amino acids). in a positive test, a copper (Il)ion ls reduced to copper (l, which forms a complex with the nitrogens and carbons of the peptide bonds in an alkaline solution. A violet color indicates the presence of proteins Procedure In this facility, Biurets reagent is always pre-made for you. Because thi contains a strong allal reagent, you should wear gloves when handling this solution. When determining how much of each reagent to use, you should try different ratios of Biuret reagent and protein to see what works best with each individual sample. The exact amount of Blurets will depend upon the protein concentration in the sampile with which you start. The ratio is not critical, but it must be the same for all of your samples. Begin by adding reagents to the test tubes as shown in the table below 0.95 0.9 0.6 0.0 50 u e 1.0 ml When adding samples to the tubes follow the directions below 1. 2. 3. 4. Add the water and the albumen together in the test tube Mix thoroughly Add-the Biuret reagent Agsin, mix thoroughly results 55 QUESTIONS . What does a positive reaction look like? Purple /Voiet 2. What does a negative reection look ike? ight blue 3. Why do you think that you are testing a range af concentrations? . How does the reaction beheve when you add increasing amounts of albumen to your tubes? What is the significance of this- in other words, could you use this reagent to determine relative amounts of protein in an unknown sample- and why? What is the purpose of adding decreasing amounts of water as you move from tube 1 through tube 67 5. . A positive control inwolves the use of an Indicator with a sample that is known to have the substance for which you are testing In this way, you will be certaln that your test is accurate and that your indicator is working. What substance in your tubes is your pasitive contrel?Explanation / Answer
Answer 1: In biuret test, when biuret reagent reacts with protein, it turns in to purple or violet color.
Answer 2: In negative reaction, the tube does not have protein (albumin) due to which it remains light blue in color, the color of biuret reagent.
Answer 3: As we see the color of the tubes from 2 to 5 the color changes from light blue to dark purple/violet. Hence it indicates that the color of tube changes with an increase in the concentration of albumin protein after reaction with biuret reagent.
Answer 4: Yes this reagent can be used to determine the relative concentration of protein in the unknown sample because as the concentration of protein increases the color will increases. By comparing the standard set of concentration we can determine the concentration of the unknown sample.
Answer 5: To prepare the standard dilution of albumin protein in tubes.
Answer 6: The albumin protein which reacts with the biuret reagent and gives purple color, hence the protein is the component which gives the color in positive control.