Lab Activity 8 Proteins part II. IUG, Spring 2014 Dr. Tarek Zaida. Experiments. A.A can be characterized qualitatively by using several dyes that will react with certain groups of the A.A. Seven Tests: Ninhydrin 4. Xanthoproteic 7. Sakaguchi Biuret 5. Hopkin’s - Cole
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Lab Activity 8Proteins part II
IUG, Spring 2014
1. Label 6 cleaned, drained test tubes with the names of the following solutions: 2 % glycine, 1 % tyrosine, 2 % proline, 2 % casein, 2 % gelatin, 2 % albumin.
2. Add 15 drops of each solution in the corresponding test tube.
Remove the test tubes from the water bath and place then in a test tube rack.
Record your observations!
1. To 1 ml of a solution containing protein add 4 ml of a biuret reagent.
2. Mix well, then let to stand at RT for about 30 min.
3. Record your observations!
Sulfur-containing protein ----> NaOH----> S2- ----Pb2+----> PbS
1. Place 1 ml of 2% casein, 2% egg albumin, 2% peptone, 2% gelatine and 0.1 M cysteine into separate, labeled test tubes.
2. Add 2 ml of 10 % aqueous sodium hydroxide. Add 5 drops of 10 % lead acetate solution.
3. Stopper the tubes and shake them. Remove the stoppers and heat in a boiling water bath for 5 minutes. Cool and record the results.
2. The formation of a red color indicates the presence of a guanidinium group in the compound under examination.