If each of the following amino acid side chains is present in the active site of an enzyme, indicate whether it would (a) serve a catalytic function, (b) serve to hold the substrate, or (c) both.
a. aspartate <IMAGE>

Verified step by step guidance

1. Aspartate is an amino acid with a side chain that contains a carboxylate group (-COO^-).
2. The carboxylate group is negatively charged at physiological pH, which can participate in ionic interactions.
3. (a) Catalytic function: Aspartate can act as a nucleophile or participate in acid-base catalysis due to its ability to donate or accept protons.
4. (b) Holding the substrate: The negative charge on the carboxylate group can form ionic bonds with positively charged groups on the substrate, helping to stabilize the substrate in the active site.
5. Therefore, aspartate can serve both (a) a catalytic function and (b) to hold the substrate.

Key Concepts

Amino Acid Side Chains

Amino acid side chains, or R groups, determine the chemical properties and functions of amino acids in proteins. They can be polar, nonpolar, acidic, or basic, influencing how they interact with substrates and other molecules. Understanding the nature of these side chains is crucial for predicting their roles in enzyme activity, including catalysis and substrate binding.

Enzyme Active Site

The active site of an enzyme is a specific region where substrate molecules bind and undergo a chemical reaction. The structure and chemical environment of the active site are tailored to facilitate the conversion of substrates into products. The presence of specific amino acid side chains in this region can enhance catalytic efficiency or stabilize substrate binding.

Catalytic Function vs. Substrate Binding

Catalytic function refers to the ability of an enzyme to accelerate a chemical reaction, often involving specific amino acids that participate directly in the reaction mechanism. Substrate binding, on the other hand, involves interactions that hold the substrate in place for the reaction to occur. Some amino acids can fulfill both roles, making it essential to analyze their properties to determine their specific contributions.