CHAPTER 20: Unit 8. Enzyme Inhibition

The activity of none allosteric enzymes can be inhibited by the binding of specific molecules or ions which are smaller in size to the none allosteric enzymes sites. These smaller ions or molecules are inhibitors

Inhibitors prevent the substrate from binding to the active sites of the enzymes.

Reference: https://socratic.org/biology/enzymes/inhibitors-competitive-and-non-competitive

There are two types of inhibitors:

1. Reversible inhibitorThe enzyme with a reversible inhibitor can regain the enzyme activity. The enzyme during the presence of a reversible inhibitor has no activity. The reversible inhibitor cannot form covalent bonds with the enzyme.There are two types of reversible inhibitors:Competitive Inhibitors: use the active site of the enzymeNoncompetitive Inhibitors: use another site that is not active site of the enzyme The figure below illustrates the difference between both reversible inhibitors:

Reference: https://socratic.org/biology/enzymes/inhibitors-competitive-and-non-competitive

Reference: https://www.quora.com/What-is-a-reversible-and-irreversible-inhibitor

2. Irreversible inhibitorThe enzyme with the irreversible inhibitor cannot regain the enzyme activity. The irreversible inhibitor can destroy the enzyme activity. Irreversible inhibitor forms covalent bond with R group of an amino acids with the active site of the enzyme which will prevent the substrate to bind to the active site and no reaction occurs. The irreversible inhibitor becomes part of the enzyme structure and the active sites of this enzyme are blocked.

Reference: https://www.quora.com/What-is-a-reversible-and-irreversible-inhibitor

Reference: Purves’s Life: The Science of Biology, 7th EditionThe videos below illustrate the reversible versus irreversible inhabitation:

Some Irreversible Inhibitors (Poisons) are given in the tables below:

Reference: https://saylordotorg.github.io/text_the-basics-of-general-organic-and-biological-chemistry/s21-08-enzyme-inhibition.html

Reference: https://www.sciencedirect.com/topics/chemistry/enzyme-inhibitor