Enzyme Regulation Graphic

Emma Eriksen Josh Marquez Alex Xochicale Brianna Chang Regulatory Mechanism of Competitive Inhibition

1. This image shows an example of competitive inhibition of an enzyme. It is captioned ‘Competitive Inhibition of an Enzyme.”

2. Competitive inhibition works by interrupting the effective creation of an enzyme-substrate complex.

As seen in the drawing, a molecule with a similar shape as a specific substrate will bind to a specific enzyme with the corresponding active site. Once the molecule, known as an inhibitor, bonds with the enzyme, the substrate that is typically involved in the creation of the enzyme-substrate complex is unable to bond with the enzyme. However, competitive inhibition is not as effective as allosteric inhibition, since both the inhibitor and the substrate bond at the same site. Competitive inhibition can fail to regulate the inactivation of an enzyme if the production of a substrate increases.

3. Competitive inhibition of enzymes can be compared to a manufacturing machine. The machine is meant to produce a product that can be used. However, if the machine’s gear are jammed by another substance, then the machine cannot create the product it is supposed to. This is similar to the method of enzyme regulation of competitive inhibition. When the enzyme is “jammed” with the inhibitor, it is unable to produce the product that would be made with the substrates.

4. Many drugs and poisons are enzyme inhibitors, since they prevent enzymes from working correctly.

For example, cyanide is a very effective competitive inhibitor of the enzyme known as “cytochrome c oxidase.” A cyanide compound is any compound with a carbon atom triple-bonded to a nitrogen atom.

Cyanide acts as a competitive inhibitor in the last part of the process of cellular respiration, which is the electron transport chain. Cyanide acts as a poison by preventing ATP from being made, and since ATP is the “universal energy source” in living organisms, any disruption in its production is often lethal. In particular, the central nervous system and the heart are heavily affected by the competitive inhibitor of cyanide.