1. Analyze the following results. in the presence of non-fat milk? Why or why no
ID: 276506 • Letter: 1
Question
1. Analyze the following results. in the presence of non-fat milk? Why or why not? If the a. Did the Bradford reagent turn blue b. Did the Bradford reagent turn blue in the presence of the tryptophan solution? Why or why c. Did the Biuret reagent turn purple in the presence of non-fat milk? Why or why not? If the d. Did the Biuret reagent turn purple in the presence of the tryptophan solution? Why or why results were unexpected, can you explain why this would happen? not? If the results were unexpected, can you explain why this would happen? results were unexpected, can you explain why this would happen? not? If the results were unexpected, can you explain why this would happen? D (Ctr)Explanation / Answer
a. Yes, the Biuret test gives blue color. The Bradford reagent is made up of sodium hydroxide, hydrated copper(II) sulfate, and potassium sodium tartrate. When two or more peptide binds present in the sample, the when reacts with alkaline copper sulphate, form coordination complex of cupric ions with the electron pairs of peptide nitrogen and oxygen of water.
If the results were unexpected it could be due to presence of only free amio acids and absence of any peptide bond. It could be due to the variation in the reagent preparation. It do not give result in presence of free amino acids.
b. In presence of only biuret reagent the tryptophan will not turn the reagent into blue but if we add nitric acid in this reaction, it will give positive result.
Biuret is negative for tryptophan solution because it do not have free NH2 to react with cupric ions.
c. Yes the skimmed milk will give positive result of Biuret test, as it has many caseins that will form many peptide bonds that will react with the copper ion and turn the reagent blue/purple.
d. Question id repeat of b part.
Ans2.
Sample
Bradford reagent
Biuret reagent
Tryptophan
blue
Pink
Non Fat Milk Protein
Blue
Blue
Control
Red
Pink
Sample
Bradford reagent
Biuret reagent
Tryptophan
blue
Pink
Non Fat Milk Protein
Blue
Blue
Control
Red
Pink
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