Could someone please explain to me the types of irreversible inhibition vs the reversible inhibition types?

Hi Sara (and thank you Youssef for your detailed answer!)

Indeed as Youssef mentioned, irreversible inhibition occurs when some covalent modification occurs on the enzyme, permanently eliminating it. This cannot be overcome by adding more substrate.

However, the most common type of enzymatic inhibition you will see on the MCAT (and a very high yield topic) is reversible inhibition. They are reversible because the inhibitor that binds to the enzyme will eventually come off. They temporarily deactivate the enzyme in contrast to irreversible ones that destroy the enzyme all together.

The 4 types of reversible inhibitors you will see on the MCAT are competitive, non-competitive, uncompetitive, and mixed inhibition.

In competitive inhibition: An inhibitor will bind to an enzyme and block binding of the substrate. This is called competitive inhibition, because the inhibitor “competes” with the substrate for the enzyme.

In noncompetitive inhibition, the inhibitor doesn't block the substrate from binding to the active site. Instead, it attaches at another site and blocks the enzyme from doing its job.

In uncompetitive inhibition, the inhibitor binds selectively to the enzyme-substrate (ES) complex.

Mixed inhibition is a type of enzyme inhibition in which the inhibitor may bind to the enzyme OR the enzyme substrate complex, but typically has a greater affinity for one or the other.

Hope this helps! - Sydney