1. Enzymes What are enzymes? Specialized proteins What do they do?
They act as catalysts in chemical reactions in our bodies.

2. What’s a catalyst?
A catalyst is a substance that brings about a reaction without being changed in the reaction.
Enzymes increase the rate of reaction in our body at least 1 million times

3. Action of Catalysts:
Basically, here’s what catalysts do:

4. Enzymes continued… The object enzymes work upon are called substrates.
Most enzymes are named according to what they work upon.
The way this is done is by changing the ending of the substrate to –ase.

5. Naming Enzymes!!! Let’s do some examples: Substrate Enzyme Sucrase
Sucrose
Lipid
Lipase
Protein
Protease

6. How do enzymes work?
Enzyme activity relies completely on the shape of the protein (remember, enzymes are proteins…).
Each enzyme works on ONE (1) and only ONE (1) substrate

7. Enzymes working continued…
Surface of each enzyme is a region called the active site.
The active site fits the shape of the substrate the enzyme works on.

8. Examples of active sites:

9. More active sites:

10. How do enzymes and substrates fit together?
There are 2 main theories as to how this happens:
1) Lock-and-Key Model
2) Induced-Fit Model

11. Lock-and-Key Model
Enzyme have a rigid structure (like a key), that fits one specific substrate (the lock).

12. Lock-and-Key Model + +

13. Induced-Fit Model Enzyme is not rigid
It changes shape when it comes into contact with a substrate.
Based on recent studies, the induced-fit model is the accepted theory as to how enzymes function.

14. Induced-Fit Model + +