Experiment No. 2 AMINO ACIDS AND PROTEINS   Data Solubility in water Sample Solubility (Soluble, Partially Soluble, Insoluble) Color with red litmus paper Color with blue litmus paper Is the solution acidic, basic, or neutral? alanine         glutamic acid         arginine         albumin                         Color Reactions of Amino Acids Ninhydrin Test Color of Ninhydrin solution:    ___________________________________   Sample Color original solution Color with Ninhydrin Color after 10 min. alanine       glycine       glutamic acid       tyrosine       albumin         Biuret Test Color of 3% CuSO4 solution:  _____________________________________   Sample Color of original solution Color after NaOH/CuSO4 casein     alanine     albumin     gelatin     distilled water       Molisch Test Color of Molisch reagent:  _____________________________________   Sample Color of original solution Color after Molisch Reagent Color at the interface glutamic acid       casein       gelatin         Xanthoproteic Test Color of concentrated HNO3: ___________________________________   Sample Color of original solution Color after HNO3 Color after NH4OH glutamic acid       tyrosine       casein       albumin       gelatin         Millon’s Test Color of Millon’s reagent: _____________________________________   Sample Color of original solution Color after Millon’s Reagent Color after 5 min. glutamic acid       tyrosine       casein       albumin       gelatin                           Test for Sulfur Color of lead acetate solution: __________________________________   Sample Color of original solution Color after NaOH Color after lead acetate glutamic acid       cysteine       casein       albumin         Sakaguchi Test Color of alpha-napthol solution: _________________________________   Sample Color of original solution Color after NaOH/ alpha-napthol Color after hypochlorite/urea arginine       glutamic acid       casein       albumin         Coagulation of Proteins   Observation fresh egg albumin   egg albumin after heating   egg albumin + nitric acid   egg albumin + ethyl alcohol     Precipitation by Heavy Metals   Observation fresh egg albumin   egg albumin + lead acetate   egg albumin + mercury (II) chloride   egg albumin + silver nitrate            Precipitation by Alkaloidal Agents   Observation fresh egg albumin   egg albumin + tannic acid   egg albumin + picric acid   egg albumin + trichloroacetic acid     Questions What is the positive result to the following tests? Ninhydrin Test: _______________________________________________ Biuret Test: _______________________________________________ Xanthoproteic Test: _______________________________________________ Millon’s Test: _______________________________________________ Test for Sulfur: _______________________________________________ Sakaguchi Test: _______________________________________________   What sample show a positive result with the Molisch Test? Why did this sample give a positive result? _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________   What is the chemical basis of the Xanthoproteic Test? Give the chemical reaction involved. _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________             Egg white and milk are used as antidotes for heavy metal poisoning.  Explain. _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________   According to advertisements, commercial shampoo or conditioner contains ‘‘protein.’’ Suggest a test that could be done on the product to check this claim? Explain your answer. _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________