Just as enzymes act like a catalyst to biomechanical reactions, there are also molecules that can affect the activity of the enzymes. Enzymatic activators are molecules that can increase the activity of an enzyme.
Examples of enzymatic activators are cofactors and coenzymes. Cofactors are usually metal ions and do not directly bind the enzyme to increase the activity of that specific enzyme. Coenzymes are usually organic molecules, which directly bind the enzyme to increase the activity of that specific enzyme.
Essential Enzymatic Activators
Essential enzymatic activators are those activators that are necessary and need to be present for enzyme activity to occur. For example, kinase is an enzyme that is responsible for phosphorylation, which makes it essential for human physiology, as it controls metabolism, regulation of cell signaling, and many other cell processes. However, kinase is an enzyme that requires the need of an activator. This activator is magnesium. Generally, two molecules of magnesium are needed for proper function of kinase to aid in the physiological health of the body.
Non-Essential Enzymatic Activators
Non- essential enzymatic activators are activators that do not necessarily need to be present for enzyme activity to occur. The reaction bought about by non-essential enzymatic activators can also be known as allosteric regulation. In the absence of the enzymatic activator, the enzyme is still in function and can bring about a biomechanical pathway. However, in the presence of the enzymatic activator it binds to the enzyme (at a place other than the active it) and increases its affinity to bind to the substrate. An example of a non- essential enzymatic activator is chloride and amylase. Amylase is a digestive enzyme and in the absence of chloride, it is seen that amylase does not perform as well as to when chloride is present.
Enzymatic inhibitors are molecules that interact with enzymes and reduce its affinity for its substrate. These types of molecules are primarily used for pharmacological purposes, where the goal would be to inhibit a pathway. For example, acetylcholine is a neurotransmitter, which is extremely important for the function of the human body. Acetylcholinesterase inhibits the activity of acetylcholine, which can lead to neurodegenerative disease. In result, acetylcholinesterase inhibitors are given to inhibit the action of acetylcholinesterase.
Within enzymatic inhibitors there are reversible and irreversible inhibitors. Reversible inhibitors cause a rapid dissociation of the enzyme-inhibitor complex and can be overcome with an increase in substrate concentration. Irreversible inhibitors cause a slow dissociation of the complex and cannot be overcome by an increase in substrate concentration. Irreversible inhibitors alter the active site of the enzyme and ultimately cause the enzyme to be unable to act as a catalyst.
There are also enzymes that fall within the category of competitive and non- competitive inhibitors. Competitive inhibitors bind the enzyme at its active site. This active site is where the enzyme will bind the substate and catalyze the biomechanical reaction. Now, if the active site is occupied by another molecule, then the substrate cannot bind, which means the reaction cannot take place. This is known as competitive inhibition because the competitive inhibitor binds at the active site preventing substrate binding. Non-competitive inhibitors differ from competitive inhibitors in that they do not bind directly to the active site. Rather, these inhibitors bind to another site on the enzyme, altering the conformation of the active site, which then makes it unable to bind to the substrate.
How Does a Competitive Inhibitor Slow Enzyme Catalysis?
Competitive inhibitors slow enzyme catalysis because they do not allow the enzyme to bind to the active site. An active site is a site locate on the enzyme and where it binds the substrate. This joining of the substrate at the active site forms a complex which allows the products of the reaction to form. With competitive inhibition, the active site is already occupied with an inhibitor, which means that the substrate cannot bind the enzyme active site, which hinders the reaction from occurring.
How Does a Non-Competitive Inhibitor Reduce an Enzyme's Activity?
Non- competitive inhibitors reduce an enzymes activity through allosteric regulation. In non- competitive inhibition, the inhibiting molecule does not bind to the active site of the enzyme. Rather, the inhibitor binds at a different site on the enzyme, which then changes the conformation of the active site on the enzyme. Now that the active site has a different 'shape', it cannot bind to the substrate, which means that it reduces the enzyme's activity.
- Enzymes are catalysts that that bring about a reaction by binding to a substrate
- Enzymatic activators increase the activity of an enzyme
- Enzymatic inhibitors decrease the activity of an enzyme
- Essential enzymatic activators are necessary for enzymatic activity to occur
- Non-essential enzymatic activators are not necessary for enzymatic activity to occur but their presence may increase enzymatic activity
- Reversible inhibitors have a rapid dissociation of the enzyme-inhibitor complex and this can be overcome by an increase in the substrate concentration
- Irreversible inhibitors have a slow dissociation of the enzyme-inhibitor complex and cannot be overcome with an increase in substrate concentration
- Competitive inhibition is when the inhibitor binds directly at the active site of the enzyme, preventing it from forming the enzyme-substrate complex
- Non-competitive inhibition is when the inhibitor binds the enzyme at a site other than the active site and causes a conformation change at the active site of the enzyme which then prevents it from forming the enzyme-substrate complex