What type of interaction would you expect between the side chains of each of the following pairs of amino acids in the tertiary structure of a protein?
d. glutamine and arginine

Verified step by step guidance

1. Identify the side chains of glutamine and arginine. Glutamine has an amide group in its side chain, while arginine has a guanidinium group.
2. Consider the nature of these side chains: Glutamine's side chain is polar and can form hydrogen bonds, while arginine's side chain is positively charged and can participate in ionic interactions.
3. Determine the type of interaction possible between these side chains. Since glutamine can form hydrogen bonds and arginine is positively charged, they can interact through hydrogen bonding.
4. Visualize the interaction: The amide group of glutamine can form a hydrogen bond with the guanidinium group of arginine, where the hydrogen from the amide group interacts with the nitrogen atoms in the guanidinium group.
5. Conclude that the interaction between glutamine and arginine in the tertiary structure of a protein is likely to be a hydrogen bond due to the polar nature of glutamine and the ability of arginine to participate in hydrogen bonding.

Key Concepts

Amino Acid Side Chains

Amino acids have unique side chains (R groups) that determine their chemical properties and interactions. These side chains can be polar, nonpolar, acidic, or basic, influencing how amino acids interact with each other in a protein's tertiary structure. Understanding the nature of these side chains is crucial for predicting interactions between specific amino acids.

Hydrogen Bonding

Hydrogen bonding is a type of non-covalent interaction that occurs when a hydrogen atom covalently bonded to an electronegative atom, like oxygen or nitrogen, is attracted to another electronegative atom. In the context of glutamine and arginine, the polar side chain of glutamine can form hydrogen bonds with the positively charged side chain of arginine, stabilizing the protein structure.

Ionic Interactions

Ionic interactions occur between positively and negatively charged side chains of amino acids. In the case of arginine, which has a positively charged side chain, it can interact with negatively charged groups or polar side chains, potentially including the amide group of glutamine. These interactions are significant in maintaining the stability and functionality of protein structures.