3. How does the form of enzymes relate to their function?

4. Target 2.11 – Enzyme Form
In which organic class would you place enzymes? A) Carbohydrates B) Lipids C) Proteins D) Nucleic Acids

5. ENZYME FORM
Enzymes are intricate, highly folded proteins made of thousands of amino acid monomers.

6. Target 2.11 – Enzyme Form
What is name of the molecule(s) with which an enzyme reacts in a chemical reaction? A) Substrates B) Surfactants C) Competitors D) Active Sites

7. SUBSTRATES
The molecule that interacts with an enzyme in a chemical reaction is the substrate.

8. Target 2.11 – Enzyme Form
In the equation below, which substance is the substrate? A) Hydrogen Peroxide B) Catalase C) Water D) Oxygen Gas

9. CATALASE & H2O2
In the decomposition of hydrogen peroxide into water and oxygen gas, hydrogen peroxide is the substrate, catalase is the enzyme and water & oxygen are the products

10. Target 2.11 – Enzyme Form
In the diagram below, what type of reaction is being catalyzed by sucrase? A) Neutralization B) Dehydration Synthesis C) Hydrolysis D) Homeostasis

11. SUCRASE
Sucrase catalyzes the hydrolysis of the disaccharide sucrose into the monosaccharides glucose and fructose

12. Target 2.11 – Enzyme Function
How does an enzyme catalyze a chemical reaction with a substrate?
By buffering the addition of H+ or OH- ions
By raising the temperature of the system
By reducing the number of substrate molecules in the reaction
By reducing the activation energy of the reaction

13. Enzymes & EA
Enzymes reduce the activation energy (EA) necessary for a chemical reaction to proceed.

14. Target 2.12 – Enzyme Specificity
Where must the enzyme pair with the substrate in order for it to function properly?
Functional Group
Active Site
Nucleation Site
β-Glycosidic Linkage

15. The Active Site
Enzymes pair with their substrates at the active site. Other substances may compete for access to this site, preventing chemical reactions.

16. Target 2.12 – Enzyme Specificity
To what does the “lock & key hypothesis” refer?
How enzymes must be unlocked by co-enzymes before they can function
How competitive inhibitors lock out enzymes by binding to the substrates
That every enzyme reacts with two substrates
That each enzyme can only pair with one specific substrate

17. Lock and Key Hypothesis
The lock and key hypothesis describes the 1:1 specificity of enzyme to substrate. Only one substrate can match the active site of any particular enzyme

18. Back to the apples…

19. Catechol
Substrate molecule found in the fleshy tissue of many fruits like apples, bananas, pears

20. Catechol Oxidase
Enzyme that reduces the activation energy needed to oxidize catechol

21. Formation of Antimicrobial
The substrate catechol combines with catechol oxidase at the active site, allowing for oxidation of catechol
The resultant product is ortho- or benzoquinone, a natural antimicrobial

22. Melanin
Ortho-quinone then reacts with oxygen gas in the presence of the enzyme tyrosinase to produce melanin
Melanin produces the color change to brown, similar to how your body tans when exposed to sunlight.

23. How do you prevent the production of melanin in fruit?

25. WHY?

26. DENATURATION
Altering the shape of an enzyme in this manner is called DENATURATION
When an enzyme is denatured, it does not fit with the substrate
Activation energy requirements return to their normal level, which is often too high for the reaction to proceed at normal temperatures
Denaturation is usually not reversible.

28. What Other Factors May Affect The Rate of Enzymatic Reaction

29. Concentration and Reaction Rate
Because the relationship between substrate and enzyme is so specific, changing the number of enzymes reacting with the substrate (or vice versa) may affect the rate of reaction
Ex: Vmax

30. Temperature and Reaction Rate
Temperature is a measurement of molecular speed
At a lower temperature, molecules collide less frequently
At higher temperatures molecules collide more frequently
Enzymes tend to have an optimal temperature at which they function