1. WHAT AFFECTS ENZYME ACTIVITY?
1) ORDER OF AMINO ACIDS
2) PROTEIN DENATURATION:
When the structure of a protein is changed due to an external stress.
If enzyme’s shape is changed  shape of the active site changed  function of the enzyme will change.
TEMPERATURE pH
3) INHIBITORS
4) SUBSTRATE CONCENTRATIONS

2. 1) ORDER OF AMINO ACIDS Wrong order = wrong shape = can’t do its job!
folded protein
active site
chain of amino acids
DNA
right shape!
active site shape
Changed!
DNA
wrong shape!

3. 2A) DENATURATION - TEMPERATURE
Optimum temperature
greatest number of collisions between enzyme & substrate
human enzymes:
35°- 40°C (body temp = 37°C)
Raise temperature (boiling)
denature protein = unfold = lose shape
Lower temperature T°
molecules move slower
fewer collisions between enzyme & substrate

4. Temperature 37° Optimal Temperature human enzymes reaction rate
What’s happening here?!
human enzymes
37°
reaction rate
temperature
Not enough heat!
Particles move slower  less collisions between enzymes and substrates  less reactions
Too much heat!
Enzymes denature  active site changes shape  substrate doesn’t fit  less reactions

5. 2B) DENATURATION - pH Effect on rates of enzyme activity
changes in pH changes protein shape
Denatures
most human enzymes = pH 6-8
depends on where in body
pepsin (stomach) = pH 3
trypsin (small intestines) = pH 8
Optimal pH
Not too acidic and not too basic.

6. pH 1 2 3 4 5 6 7 8 9 10 11 12 13 14 stomach pepsin intestines trypsin
What’s happening here?!
reaction rate 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH
Each enzyme has its own optimal pH
If too acidic or basic  enzyme denatures  active site changes  no reaction
What is pepsin’s optimal pH? __________ Trypsin? ____________

7. 3) ENZYME INBHIBITORS Two kinds of Inhibitors Competitive Inhibitors
Enzymes control biochemical processes by increasing the rate at which they occur.
Too much activity means– build up can be dangerous to the cell. too much product
Enzyme Inhibitors: turns enzymes on or off.
Two kinds of Inhibitors
Non-competitive Inhibitors
- Molecule binds to site other than active site.
- Causes enzyme to change shape – substrate can’t bind
Competitive Inhibitors
- Molecule (not substrate) binds to active site
- Blocks substrate

8. Harmful Enzyme Inhibitors
Inhibitors are usually beneficial: they control the rate at which reactions occur
No inhibitor: fast
Inhibited: slow
Some inhibitors are harmful
Eg. Nerve Agent – inhibitors that interfere with nerves. First developed in WWII.
Eg. Sarin
Result?
Nerves continuously fire  muscles not able to relax  muscles seize  breathing & heartbeat affected, victim paralyzed.
Inhibitor
Sarin
Competitively inhibits acetylcholinesterase.
Enzyme
Acetylcholinesterase
Responsible for digesting acetylcholine.
Substrate
Acetylcholine
Causes nerves to fire continuously as long as its present.

9. 4) SUBSTRATE CONCENTRATION

10. Enzymes still available
Enzymes occupied
Most enzyme’s active sites are occupied, so adding more substrate does not increase reaction rate.
Enzymes still available
Increasing substrate concentration will increase reaction rate.
Saturation Point
Point at which all active sites are occupied.
What’s happening here?!
reaction rate
Substrate concentration

11. HOW TO SPEED UP CHEMICAL REACTIONS (AND GET A DATE)
In the video, there are 5 parallels between getting a date and speeding up a chemical reaction. Fill in the following table.
Change to School to increase chance of getting a date.
Change to variable to speed up chemical reaction.
Shrink size of hallways – more chance for students to collide.
Increase population of school – more chance for students to collide
Increase temperature of a reaction – particles move faster
Increase total surface area
Hire a matchmaker – makes it easier for a couple to get together by coordinating the match.