OPEN ENDED: In a laboratory a scientist is experimenting with a synthetic enzyme called “hydrolase”. The goal of this enzyme is to bind to intracellular water and speed up hydrolysis RXNs within the cell, so that cells can break apart any polymer at a much faster rate than normal. Describe the mechanisms by which a competitive inhibitor and a non-competitive inhibitor could act on this enzyme.
Competitive inhibitors are substances which compete with the substrate by binding to the enzyme's active site, and making the enzyme unavailable to act on the substrate.
In this case, the competitive inhibitor would bind to the enzyme so the the target hydrolysis molecules would not be able to do so.
Non competitive inhibitors act somewhere other than the active site. The react with sites known as 'allosteric sites', or some other sites, which take away the ability of the enzyme to bind to the substrate. That enzyme molecule becomes unable to perform catalysis for the reaction.
To understand how competitive and non-competitive inhibitors can act on the synthetic enzyme "hydrolase," we need to first understand their mechanisms of action.
1. Competitive inhibitor:
A competitive inhibitor competes with the substrate for the active site of the enzyme. It binds reversibly to the active site, forming an enzyme-inhibitor complex. The binding of the competitive inhibitor prevents the substrate from binding, thus reducing the enzyme's activity.
In the case of "hydrolase," a competitive inhibitor might bind to the active site of the enzyme, preventing water molecules from binding. As a result, the substrate does not bind properly to the enzyme, reducing the rate of hydrolysis reactions within the cell. However, it's important to note that the competitive inhibitor does not affect the catalytic activity of the enzyme; it merely competes with the substrate for binding to the active site.
To determine whether a compound acts as a competitive inhibitor, the scientist could perform an experiment where she measures the initial reaction rate of the enzyme in the presence of increasing concentrations of a potential competitive inhibitor. If the inhibitor is competitive, increasing its concentration can overcome its inhibitory effect and restore enzyme activity. This demonstrates that the substrate and inhibitor are competing for the same active site on the enzyme.
2. Non-competitive inhibitor:
Unlike a competitive inhibitor, a non-competitive inhibitor does not compete with the substrate for the active site. Instead, it binds to a different site on the enzyme called the allosteric site. This binding causes a conformational change in the enzyme, altering the active site's shape and inhibiting the enzyme's activity.
In the case of "hydrolase," a non-competitive inhibitor could bind to the enzyme in a region other than the active site. Once bound, the inhibitor induces a change in the enzyme's shape, disrupting the catalytic activity of the enzyme. This inhibitory effect is often irreversible, as the binding of the inhibitor is not easily dissociated.
To determine whether a compound acts as a non-competitive inhibitor, the scientist could perform an experiment where she measures the initial reaction rate of the enzyme in the presence of increasing concentrations of a potential non-competitive inhibitor. If the inhibitor is non-competitive, its presence will reduce the enzyme's activity regardless of the concentration of the substrate. This indicates that the inhibitor binds to a site other than the active site, resulting in a change in enzyme conformation and reduced enzymatic activity.
In summary, a competitive inhibitor competes with the substrate for the active site, while a non-competitive inhibitor binds to an allosteric site, resulting in enzyme inhibition through a conformational change. By understanding the mechanisms of both these inhibitors, scientists can gain insights into how the activity of the synthetic enzyme "hydrolase" can be regulated and potentially manipulated for different purposes.