1. Enzymes

2. Enzymes We have previously learned that enzymes are protein catalysts
We also learned the chemical that is being acted upon by an enzyme is called the substrate
Today we are going to dive deeper into what an enzyme does, how it functions and why it is so important to a cell

3. Enzymes Both catalysts and enzymes work by lowering activation energy
Activation energy is an energy barrier that must be overcome for reactions to proceed
You may see them notated as EA

4. Enzymes
Enzymes lower the activation energy needed for a reaction to take place
This is a great thing for your cells because it allows reactions to happen faster and with more complete results

5. Enzymes Take a look at the reaction to the left
The pathway in red requires a large amount of activation energy
The pathway to the right requires less than half of the activation energy needed to start the reaction

6. How Do Enzymes Work? How do enzymes work?
How do they lower activation energy?
Is it magic?

7. How Do Enzymes Work? Enzymes bend chemicals into unstable positions
The bonds from the substrate bend to a highly unstable angle and can be much more easily broken

8. Video PLEASE DO NOT WATCH UNLESS YOU ARE NOT SQUEEMISH!!!
Someone breaks their humerus in the second video
It is not humorous
It is quite alarming… but it demonstrates a very valid scientific point
You have been warned…

9. How Do Enzymes Work?
The area when an enzyme binds with a substrate is called the active site
The substrate must fit very specifically into the enzyme’s active site
If it does not fit specifically then the enzyme does not work
If the substrate does not fit into the active site, the bonds will not be bent in the correct fashion

10. Sucrase
One good example of an enzyme and substrate is the enzyme sucrase
Sucrase is an enzyme that works on the molecule sucrose
Notice its –ase ending
That designates it as an enzyme

11. Sucrase

12. When Enzymes Don’t Work
Enzymes are very specifically shaped
If their active site changes shape, they cannot function as effectively as normal
This means that anything that changes an enzymes shape will cause it to be less effective

13. When Enzymes Don’t Work
Heat, pH and other factors can denature enzymes
Denaturing an enzyme is when you change the active site of that enzyme
Enzymes are mostly specifically designed to work in the environment that they are in

14. Other Enzyme Fun… Sometimes enzymes can be stopped
This is called enzyme inhibition
This can happen if a competitive molecule blocks the active site through competitive inhibition
It can also happen if a noncompetitive inhibitor blocks the enzyme from doing its job

15. Other Enzyme Fun… Some enzymes need help
This help comes from cofactors
Cofactors are things like zinc, iron and copper that help bend the active site to fit the substrate