What are the types of reversible inhibition of enzymes?

Reversible inhibition of enzymes occurs when reversible inhibitors bind to enzymes via non-covalent interactions such as ionic bonds, hydrogen bonds, and hydrophobic contacts. 

There are 4 types of reversible inhibition of enzymes: 

1. Competitive Inhibition – In competitive inhibition, a molecule other than the substrate (an inhibitor) binds to the enzyme's active site and blocks it, preventing the substrate from binding to the site. As the substrate competes with the inhibitor, increasing the substrate concentration suppresses the inhibitor’s actions, allowing the reaction to proceed. 
2. Non-Competitive Inhibition – When an inhibitor binds to a location other than the active site known as the allosteric site. It results in non-competitive binding. In this case, the inhibitor prevents the substrate from binding indirectly by causing the enzyme’s active site to undergo a structural change so it no longer shares an affinity with the substrate. As the inhibitor is not in direct competition with the substrate, increasing the substrate levels will not suppress the inhibitor’s actions in non-competitive inhibition. 
3. Uncompetitive Inhibition – In uncompetitive inhibition, the inhibitor binds only to the enzyme-substrate complex. While this does not affect the binding of the substrate, it reduces the catalytic efficiency of the enzyme. 
4. Mixed inhibition – Mixed inhibition occurs when a mixed inhibitor binds to both the enzyme and the substrate-enzyme complex. The binding of the inhibitor causes a conformational change in the enzyme, which hampers the binding of the substrate. Increasing the substrate concentration can reduce mixed inhibition but it cannot be completely eliminated. 

Reversible inhibition is critical in regulating enzyme activity as it does not disable enzymes and shut them down permanently.