1. Apple Experiment Come down and get an apple and a slice of lemon.
When you get back to your seat:
1. Take a big bite of your delicious apple.
2. Immediately squeeze lemon juice over the apple flesh that is now exposed from the bite.
3. IMPORTANT! Don’t get lemon juice all over the apple. Make sure that it is ONLY on the area that you just bit!
4. Set the lemon aside and wipe any lemon juice off of your hands with a napkin.
5. Take another bite from the opposite side of your apple.
6. Set your apple aside.

2. Lecture 4:
Enzymes

3. What Are Enzymes?
Enzymes are __________ (tertiary and quaternary structures).
An enzyme is a _________ in cellular reactions.
A catalyst accelerates a reaction.
proteins
catalyst

4. Enzymes Are ________ for what they will catalyze Are _________
Usually end in -_____
-Sucrase
-Lactase
-Maltase
specific
reusable
ase

5. How do enzymes work?
Each enzyme has a unique 3-D shape, including a surface groove called an ______ _____.
The enzyme works by binding a specific chemical reactant (_________) to its active site, causing the substrate to become unstable and react.
The resulting __________ is then released from the active site.
Active site
Substrate
Product

6. How do enzymes work?
Enzymes work by _______ ______ which ________ activation energy.
Weakening bonds
Lowering

7. Enzyme-Substrate Complex
The reactant an enzyme acts on is specifically called the _________.
Enzyme
Joins
Substrate
Substrate

8. ______ _____ Enzyme Active Site Substrate
A specific region of an enzyme molecule which binds to the substrate.
Active Site
Enzyme
Substrate
Active site

9. Shape of a Protein
An enzyme fits with its substrate like a ____ and ____.
Lock
Key

10. EnzymeAnimation : Gary E. Kaiser http://student. ccbcmd
EnzymeAnimation : Gary E. Kaiser View :

11. Enzymes are ____ ________ in the reactions they catalyze
Enzymes are ____ ________ in the reactions they catalyze. Think of them as tiny machines in manufacturing. The more machines, the faster the accumulation of _________.
Not consumed
Product
Image:
Wine Bottling :
Wine Vats:

12. Formats for writing a chemical reaction.
( ________ )
_______ + ________ > _________
__________ > ________ ________
Reactant, reactant, (enzyme) > product
Reactant, (enzyme) > product, product
One or more of the reactants in an enzymatic reaction is the substrate, the reactant(s) that specifically interacts with the enzyme.

13. 4 levels of Protein Structure

14. How Do You Stop an Enzyme?
_______________
• Alteration of a protein shape through some form of external stress
• Denatured protein can’t carry out its cellular function .
Denaturation
Irreversible egg protein denaturation caused by high temperature (while cooking it).

15. Factors Affecting Enzyme Activity
Temperature pH
Cofactors & Coenzymes
Inhibitors

16. Temperature & pH
Think about what kind of cell or organism an enzyme may work in…
Temperatures far above the normal range _________ enzymes (This is why very high fevers are so dangerous. They can cook the body’s proteins)
Most enzymes work best near __________ pH (6 to 8).
Denature
Neutral

17. Coenzymes & Cofactors
Non-protein substances (zinc, iron, copper, vitamins) are sometimes need for proper enzymatic activity.
• Coenzyme versus Cofactor: What’s the dif?
_________ more general term. Includes inorganic and organic molecules.
_________ type of Cofactor, But specifically organic molecules.
Cofactor
Coenzyme
Image:
EnzymeCofactor : Public domain Wiki, Ribbon-diagram showing carbonic anhydrase II. The grey sphere is the zinc cofactor in the active site.

18. Coenzyme : Vitamin B12 Example:
Most _________ are coenzymes essential in helping move atoms between molecules in the formation of carbohydrates, fats, and proteins.
• Exclusively synthesized by ___________ (found primarily in meat, eggs and dairy products).
Vitamins
Bacteria
Image: VitaminB12 : NIH, Public Domain

19. Two Types of Enzyme Inhibitors
1. ___________ ____________:
Chemicals that resemble an enzyme’s normal substrate and compete with it for the active site.
Enzyme
Competitive inhibition
Substrate
Competitive inhibitor

20. 1. Competitive inhibitors:
Resemble an enzyme’s normal substrate and compete with it for the active site.
Image: Competitive Inhibition : www-biol.paisley.ac.uk/.../chapter3_2.html

21. Two Types of Enzyme Inhibitors
_______________ ______________:
Do not enter the active site, but bind to another part of the enzyme causing the enzyme to change its shape, altering the active site.
Enzyme
Noncompetative inhibition
Noncompetitive
Inhibitor
Substrate
active site
altered

22. Enzyme Inhibitors
Blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance.
Many _____ are enzyme inhibitors.
Enzyme inhibitors are also used as _________ and __________.
Drugs
Herbicides, pesticides
Images
Dead Bug :
Prescription Drugs :

23. Featured Enzyme #1: Catecholase
Catecholase is present in most ______ and __________.
It is the enzyme that facilitates the ________ of cut or bruised fruits and vegetables by catalyzing the following reaction:
(______________)
_________ _____  _____________
colorless substrate brown product
Fruits, vegetables
Browning
Catechol + oxygen (catecholase) > polyphenol

24. Featured Enzyme #1: Catecholase & Noncompetetive Inhibition
_________ juice and other acids are
used to preserve color in fruit,
particularly apples, by lowering the ____
and removing the copper site (cofactor)
necessary for the enzyme to function.
catecholase
catechol O  polyphenol
colorless substrate brown product
Lemon pH

25. Featured enzyme #2: Bromelain
Pineapple contains enzyme bromelain, which can _______ _________.
Jell-O is made of gelatin, a processed version of a structural protein called _________ that is found in many animals, including humans.
Collagen is a big, fibrous molecule which makes skin, bones, and tendons both strong and elastic.
The gelatin you eat in Jell-O comes from the collagen in cow or pig bones, hooves, and connective tissues. (Yummie!)
Examine 2 containers:
a. In one, canned pineapple was used to make jello.
b. The other, fresh pineapple was used.
Digest protein
collagen

26. LAB: Catalase
Each enzyme is specific for the reaction it will catalyze. In this laboratory,
Enzyme = catalase Substrate = hydrogen peroxide (H2O2) Products = water and oxygen
H2O2 H2O + O2
If a small amount of catalase is added to hydrogen peroxide, you will be able to observe bubbles of ________________ forming.

28. Design of the Experiment
In this experiment, you will investigate the rate at which the enzyme catalase converts substrate to product. You will allow catalase to react with hydrogen peroxide for varying amounts of time and then stop the reactions by adding H2SO4.To determine the amount of hydrogen peroxide that remains after the reaction, you will do a titration with KMnO4. In such a titration, you slowly add a chemical (KMnO4) that will cause a color change until a target color is achieved.

30. Titration
To determine how much hydrogen peroxide (substrate) has been broken down by catalase at varying times, you measure the amount of peroxide remaining in each flask.

31. Reading the pipette
Assume that the pipette is filled to the point indicated in the figure at the left. You would record the initial point as 3.30 ml; the ending point would be 3.90 ml. Therefore, the titration would have required 0.60 ml. Remember that you should read the number that is at the bottom of the meniscus.

32. We can calculate the rate of a reaction by measuring, over time, either the disappearance of substrate (as in our catalase example) or the appearance of product (as in the above graph). For example, on the graph above, what is the rate, in moles/second, over the interval from 0 to 10 seconds?

33. Analysis of Results
so for this example, the rate would be