Enzyme Inhibition and Regulation

1. Enzyme Inhibition and Regulation CHEM&131 Spring, 2012 Nazrawie Tesfay Nafkot Nurga Senait Habtu

2. Enzyme Inhibition • Enzyme inhibitors • Are a molecule that binds with the active site of an enzyme to decreases its activity. • It stop the substrate from binding to the enzyme’s active site • It can be reversible or irreversible.

4. Competitive Inhibition • It has the same shape and chemical structure with the normal substrate. • It compete with the normal substrate for the active site of the enzyme. • It prevent the substrate from reacting with the enzyme. • No reaction occurs.

6. Non-Competitive • It does not compete with the substrate for the active site of the enzyme. • It bind to the other site of the enzyme called Allosteric site. • It causes the enzyme change its shape temporarily and makes it nonfunctional.

8. Irreversible inhibition • It is a process of restraining the enzyme from functioning by changing its chemical structure. • The inhibitor forms covalent bond with the enzyme’s active site.

9. Allosteric Enzymes • Have two receptor sites • An active site for substrates • Allosteric site for Modulators and activators

10. Enzyme Regulation • Enzyme regulation is the way of controlling the rate of reaction of the enzyme by modulator. • Enzyme regulation by inhibition can happen on the active site or allosteric site but modulation happens only on the allosteric site. • Enzyme regulation involves not only inhibition but also activation of the enzyme’s activity.

11. Modulator • modulator is a molecule that binds to the allosteric site of the allosteric enzyme and alters the active site’s shape. • Is more selective and more potent than the active site inhibition.

12. Modulator

13. Types of modulators Negative modulators: • Are types of modulators that bind to the allosteric site and change the shape of the active site, so the substrate will not be able to bind to the active site. • Are non competitive inhibitors. Positive modulators: • Are types of modulators that bind to the allosteric site and change the shape of the active site, so the substrate will be able to bind to the active site. • they activate the active site of the allosteric enzyme and we call them Activators.

14. Activator • Activator is molecule that bind to the allosteric site and it increase the enzyme's’ activity. • Activators are inorganic compounds. • Are modulators.

15. Activator

16. Modulator

17. Source • Enzyme Regulators." Enzyme Regulators. Web. 07 June 2012. <http://www.elmhurst.edu/~chm/vchembook/573regulate.html>. • "Google Books." Google Books. Web. 07 June 2012. <http://books.google.com/>. • "Allosteric Activation." Allosteric Activation. Web. 07 June 2012. <http://course1.winona.edu/sberg/animtns/allostan.htm>. • "Biosphere." Biosphere. Web. 07 June 2012. <http://faithbiology.edublogs.org/category/uncategorized/page/2/>.