1. Competitive inhibitors compete physically and structurally with the substrate for an enzyme's active site, they can be out competed by adding extra substrate. The inhibitor will have the same binding site configuration as the substrate thus meaning the enzyme will accept it. An example of competitive inhibition could be malonic acid which competes with succinate for active sites of succinic dehydrogenase, an important enzyme in the krebs cycle.
2. Non competitive inhibitors do not compete for the active site, but inhibit the enzyme by binding else where and changing the shape of the enzyme. Am example of non competitive inhibition could be cyanide which combines dehydrogenase with the cytochrome enzymes responsible for the transfer of hydrogen atoms during cellular respiration. This shows that the substrate in the active site of the enzyme.
3. Irreversible inhibitors bind directly to the active site by covalent bonds, which change the structure of the enzyme and inactivate the enzyme permanently. Most medications are enzyme inhibitors of one kind or another.
