1. Enzymes: Specialized Protein molecules

2. Flow of energy through life
Life is built on chemical reactions

3. Chemical reactions of life
Enzymes are catalysts. This means they speed up reactions by lowering the activation energy in 2 ways:
Synthesizing molecules
building
Digesting molecules
Breaking down + +

4. Examples
synthesis
enzyme +
digestion
enzyme +

5. Enzyme vocabulary Enzyme Substrate Enzyme-substrate complex
Specialized, catalytic protein
Substrate
molecule that enzymes work on
Enzyme-substrate complex
enzyme & molecule temporarily joined
Active site
part of enzyme that substrate molecule fits into

6. Enzymes are proteins Each enzyme is specific to a specific reaction
This is shown as a 3D structure because the shapes fit together
enzymes are named for the reaction they help
Examples:
sucrase breaks down sucrose
proteases breakdown proteins
lipases breakdown lipids
lactase digests lactose
Oh, I get it!
They end in -ase

7. Enzymes aren’t changed
Enzymes are not changed by the reaction
used only temporarily
re-used again for the same reaction with other molecules
very little enzyme needed to help in many reactions
enzyme
substrate
product
active site

8. It’s shape that matters!
Lock & Key model
shape of protein allows enzyme & substrate to fit
specific enzyme for each specific reaction
Reusable

9. 1 2 3

10. What affects enzyme action
Correct protein structure
correct order of amino acids
Temperature
pH (acids & bases)

11. More about Enzymes: What Affects Enzymes

12. Enzyme concentration reaction rate amount of enzyme
What’s happening here?!
amount of enzyme
reaction rate

13. Temperature Effect on rates of enzyme activity Optimum temperature
greatest number of collisions between enzyme & substrate
human enzymes = 35°- 40°C (body temp = 37°C)
Raise temperature
denature protein = unfold = lose shape
Lower temperature T°
molecules move slower
decrease collisions

14. Temperature
What’s happening here?!
37°
reaction rate
temperature

15. pH Effect on rates of enzyme activity pH changes protein shape
most human enzymes = pH 6-8
depends on where in body
pepsin (stomach) = pH 3
trypsin (small intestines) = pH 8

16. pH stomach pepsin intestines trypsin reaction rate pH 1 2 3 4 5 6 7 8
What’s happening here?!
stomach pepsin
intestines trypsin
reaction rate 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH

17. For enzymes… What matters?
SHAPE!