Q. 16.67 - An Introduction to General, Organic, and Biological Chemistry

Question

If glutamate were replaced by proline in a protein, how might the tertiary structure be affected? $(16.1, 16.3)$

Step-by-Step Solution

Answer

The replacement of the protein glutamate with proline affects tertiary structure, the reasons are 

• Within a protein, amino acids with non-polar $R$ groups gather far from the aqueous environment to form a hydrophobic center within the protein molecule.

 

Step 1: Introduction - Protein and the functions of tertiary structure

1. Tertiary structure is the three-dimensional shape of a protein. 
2. Tertiary structure includes attractive and repulsive forces between the R groups of amino acids in the polypeptide chain of a protein. 

Step 2: Given Information - Glutamate Structure We need to find The effect on tertiary structure if the protein glutamate is replaced by proline.

• The structure of glutamic acid is:        

• The amino acid is a polar acidic amino acid because of the presence of a polar group.

1. This protein causes a hydrophilic interaction  between the two polar amino acids. 
2. This is the gravitational pull between the external aqueous environment and the R group of  polar amino acids. 
3. During this attraction,  polar amino acids travel toward the outer surface of the protein, where they form hydrogen bonds with water.

Step 3: Given Information - Proline Structure We need to find The effect on tertiary structure if the protein glutamate is replaced by proline.

• The structure of Proline is:

Step 4: Explanation The effect on tertiary structure if the protein glutamate is replaced by proline.

1. The given Amino acids are characterized as non-polar amino acids. 
2. It is known that non-polar amino acids have hydrophobic interactions. 
3. This is the interaction between two non-polar $R$ groups. 
4. Within a protein,  amino acids with non-polar $R$ groups gather far from the aqueous environment to form a hydrophobic center within the protein molecule.  
5. Therefore, for these reasons, tertiary structure is affected.