THE TEST OF PROTEIN IN EGG ALBUMIN SOLUTION

Proteins are polymers of amino acids that linked through a peptide bond. Egg albumin is one of the main sources of protein. The objectives of this experiment were (1) to identify protein derived from egg by utilizing a unique bond in the protein which is peptide bond by several protein tests, and (2) to determine the effect of physical changes caused by the changing of  temperature, pH and chemical substances on the structure protein The method used in this experiment was qualitative method. Based on the result obatined, it can be concluded egg albumin solution contains protein and can be identified by several tests. The results were Biuret test showed positive results, namely a purple solution due to the formation of complex Cu²⁺; precipitation of proteins by metal HgCl₂ and Pb(CH₃COO)₂ produced white precipitate;  precipitation by salt (NH₄)₂SO₄ which produced white precipitate and its precipitate were positive in Millon test (red precipitate) and soluble in water, and then the filtrate was positive with the Biuret test (bluish solution); precipitation of proteins by alcohol produced white precipitate in the acid and buffer conditions; protein coagulation produced  white precipitate and positive in Millon test (red precipitate); and protein denaturation produced white precipitate in acid and buffer conditions. From the test that has been done,  egg contains the amino acid tyrosine, as shown on the Millon test that is specific to this amino acid. Then, the structure of protein was influenced by temperature, chemical substances and pH.

Keywords: Amino acids, Egg albumin, Biuret test, Protein precipitation by metal, Protein precipitation by salt, Coagulation test, Protein precipitation by alcohol, Protein denaturation 

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