1. Enzymes: the proteins in our body that get the chemical reactions necessary of life done
common enzyme found in nearly all living organisms which are exposed to oxygen, where it functions to catalyze the decomposition of hydrogen peroxide to water and oxygen. Catalase has one of the highest turnover numbers of all enzymes; one molecule of catalase can convert millions of molecules of hydrogen peroxide to water and oxygen per second.[2]
Human catalase

2. Review: the basics of a chemical reaction
A + B C
Reactants
Products
Energy
To be effective and save energy, cells rely on proteins (the ‘workers’ of the cell) to
bring down the “cost” of this reaction. These proteins are also known as enzymes!

3. All enzymes are proteins but not all proteins are enzymes!
Serve to reduce the activation energy required to make a chemical reaction go!
** Do you remember this?**
To costly for the cell
to get the job done alone!
It needs help!
It needs an enzyme!

4. Catabolic example: Breaking up macromolecules
Types of Enzymes
Anabolic example: Making ATP
Catabolic example: Breaking up macromolecules

5. Enzymes are catalysts!
enzymes bind specifically to a molecule and stress the bonds to make the reaction more likely to proceed
active site is a site on the surface of the enzyme that binds to a reactant
the site on the reactant where the enzyme binds is called the binding site

6. Exergonic reaction: energy is released as a product of the reaction
Fig. 6.4.b
Exergonic reaction: energy is released as a product of the reaction
Activation
energy

7. Fig. 6.4.c
Enzymes reduce the activation energy and certain catalyzed reactions will have energy release as a byproduct
uncatalyzed
Catalyzed reactions will
occur at a faster rate bc
the amount of activation
energy required to initiate
the reaction
catalyzed
Activation
energy
Chemical reactions and catalysis

8. Quick overview: How an enzyme works! The “lock and key” mechanism!
Brings the right substrates together in the right orientation to get the reaction done!

9. Lock and Key Mechanism and enzyme specificity
Fig. 6.5
Lock and Key Mechanism and enzyme specificity
Enzymes selectively recognize proper substrates over other molecules
Specificity is controlled by structure – the unique fit of substrate with enzyme controls electivity for substrate and the product yield
Substrate binding to the active site induces a conformational change in the active site

10. More on how enzymes work:
In most cases substrates are held in the active site by weak interactions
Catalyze the conversion of substrate to product
A single enzyme molecule can catalyze thousands or more reactions a second
Enzymes are unaffected by the reaction and are reusable

11. Each enzyme is unique based on its 3-D structure
Each enzyme is unique based on its 3-D structure. It has a specific chemical reaction it will participate in.
Human glyoxalase
carbonic anhydrase II
These enzymes have unique active sites, different substrates and catalyze difference reactions!

12. What effects an enzyme’s function?
Temperature and pH affect enzyme activity
enzymes function within an optimum temperature range
when temperature increases, the shape of the enzyme changes due to unfolding of the protein chains
enzymes function within an optimal pH range
the shape of enzymes is also affected by pH
most enzymes work best within a pH range of 6 - 8
exceptions are stomach enzymes that function in acidic ranges pH
scale 1 6 7 8 14

13. Effects of temperature on the function of an enzyme
Fig. 6.8
Effects of temperature on the function of an enzyme
Pepsin is an enzyme that is released by the chief cells in the stomach and that
degrades food proteins into peptides.
Trypsin is a serine protease found in the digestive system of many vertebrates,
where it hydrolyses proteins.Trypsin is produced in the pancreas

14. The effects of pH on the function of an enzyme
Fig. 6.8
The effects of pH on the function of an enzyme
Pepsin
Trypsin

15. How a cell regulates (uses) an enzyme
Feedback inhibition is a form of enzyme inhibition where the product of a reaction acts as a repressor
competitive inhibition
the inhibitor competes with the substrate for the active site
blocks the active site so that it cannot bind substrate
non-competitive inhibition
the inhibitor binds to the allosteric site and changes the shape of the active site so that no substrate can bind

16. Competitive and Non-competitive inhibition
Fig. 6.10

17. Allosteric Regulation: can inhibit or activate

18. Fig. 6.7
Biochemical pathways: the product of one enzyme reaction acts as the substrate for the next reaction

19. We can design drugs which mimic natural enzyme inhibitors to treat disease and enzyme misfunction
HIV is treated with many different types of enzyme inhibitors