Proteins: Structure, Chemical Identification & Polypeptide Synthesis

1. Using Biuret to Identify Presence of a Protein2. Learning the Chemical Structure of an Amino Acid3. Using a Dehydration Synthesis to Make a Polypeptide Chaine

Testing for Organic CompoundsPart A: Protein Testing

1. Involves an indicator, Biruet Solution2. Biuret reacts with the amino acids in the protein3. Solution color goes from blue to violet4. Color change indicates a chemical reaction between the biuret and the bonds between the amino acids of a protein

Another Look at Biuret Test

Chemistry of the Biuret Test

Negative Control

Postive Control

Experiment

Proteins• Are organic polymers composed of monomers called amino acids.• Strands of amino acids are called polypeptide chains. Where are

the peptide bonds?

Proteins are many chained structures.

Amino Acids Polypeptide Chain

Protein with twoPolypeptide chains

Where is the complete protein?

Parts of an Amino Acid

Here is another diagram of an amino acid….

Lab Safety & Cleanup• Test tubes are glass.• Biruet Solution is a base. Wash hands with water.• Goggles on at all times• Use special glassware soap and water with test tube brush to

wash all test tube• Return all materials to appropriate location• Complete data table.• On back of lab, construct (5) observation statements and then

write a conclusion.

Polypeptide Synthesis• Involves two amino acids.• Involves a dehydration synthesis.• Involves a chemical reaction that occurs between two specific

areas of the amino acid.• Requires an –OH group and an –H from another –OH group

http://www.youtube.com/watch?v=iB7B0YaSLhU

Functions of Proteins