H1 Biology and H2 Biology

Competitive Inhibitors Vs. Non-Competitive Inhibitors

Notes from the video ‘H2 Biology Tuition | H1 Biology Tuition | Competitive Inhibitors vs. Non-competitive Inhibitors’:

 

In this Biology tutorial, we would compare the differences between competitive inhibitors vs. non-competitive inhibitors.

 

Firstly, let’s compare their structures.

The competitive inhibitor has similar conformation and charge to the substrate molecule.

On the other hand, the non-competitive inhibitor does not have similar conformation and charge to the substrate molecule.

 

Secondly, let’s compare their binding site.

Competitive inhibitors bind reversibly to the enzyme’s active site.

On the other hand, non-competitive inhibitors bind to allosteric sites on enzymes. Allosteric sites are sites on enzymes that are not the active site. Some non-competitive inhibitors bind reversibly via weak bonds such as hydrogen bonds, while others bind irreversibly via strong covalent bonds.

 

Thirdly, let’s compare their effect on enzymes.

Competitive inhibitors compete with the substrate for the active site. This decreases the availability of active sites for substrate binding and leads to a reduction in the formation of enzyme-substrate complexes and the rate of reaction.

On the other hand, the binding of non-competitive inhibitors alters the conformation of the specific enzyme active site such that the enzyme is no longer complementary in shape and charge to the substrate. This forms enzyme-inhibitor complexes and reduces the availability of the enzymes for substrate binding. Rate of formation enzyme-substrate complexes decreases so the rate of reaction is reduced.

 

Lastly, let’s compare whether the effects of the inhibitors can be overcome by high substrate concentrations.

The effects of the competitive inhibitors can be overcome by high substrate concentrations. The higher portion of substrate molecules would be able to outcompete the competitive inhibitors for the active site to form enzyme-substrate complexes. At high substrate concentrations, the rate of reaction is the same as that when no competitive inhibitors are present.

On the other hand, effects of the non-competitive inhibitors cannot be overcome by high substrate concentrations.

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