1. Enzymes
They be proteins.

2. What should I Be able to do after reading about enzymes?
Understand these concepts:
Enzymes have an active site to which specific substrates bind.
Enzyme catalysis involves molecular motion & the collision of substrates with the active site.
Temp, pH & substrate concentration affect the rate of activity of enzymes.
Enzymes can be denatured.
Immobilized enzymes are widely used in industry.
Explore the Nature of Science:
Experimental design: accurate quantitative measurements in enzyme experiments require replicates to ensure reliability.
Further your understanding by studying this example:
Methods of production of lactose-free milk and its advantages.
Apply your understanding by performing this Skill:
Design of experiments in to test the effect of temperature, pH & substrate concentration on the activity of enzymes.
Experimental investigation of a factor affecting enzyme activity. (Practical 3)

3. Understanding: Enzymes have an active site to which specific substrates bind.
Globular proteins
Biological catalysts = made by cells AND speed up chem rxns without being altered themselves
Found in all cells
Specific = only catalyze one kind of rxn
SUBSTRATES:
Converted into products by enzymes
Usually smaller than the enzymes they bind to
substrate enzyme product

4. How enzymes speed up rxns:
Active site = specific region on the surface of enzyme to which substrate binds
Active site only binds to one specific substrate because the shape and chemical properties of both match up
Substrates converted into products while bound to active site of enzyme
Enzyme can be re-used after products released from active site

5. Understanding: Enzyme catalysis involves molecular motion and the collision of substrates with the active site.
Enzyme activity = catalysis of a rxn by enzyme
3 stages:
Substrate(s) binds to active site of enzyme.
Substrates converted (change) to products.
Products separate from active site, leaving it open for new substrates.
Collision = coming together of substrate and active site
Occur because of random movements of substrate and enzyme, which are both
In constant motion because most substrates are dissolved in liquid water around the enzyme. Liquids are in continual motion.

6. Two models to explain enzyme activity:
Lock and Key (1890) and Induced Fit (1959)

7. Understanding: Temp, pH & substrate concentration affect the rate of activity of enzymes.
Temperature and enzyme activity:
Increase in temp causes increase in enzyme activity – due to molecules moving faster at higher temps, which increases chances for random collisions
Too much heat decreases enzyme activity – due to increasing chances of bonds breaking in enzyme because of vibrations, which causes denaturation

8. pH and enzyme activity:
Slight pH increases or decreases from the optimum reduces enzyme activity – due to slightly altering shape of active site so sometimes substrate doesn’t fit
Extreme pH increases or decreases from the optimum will denature enzyme

9. Different enzymes have diff pH optimums!
Biological laundry detergent contains a protease made by B. licheniformis, which has pH optimum of 9-10.

10. Substrate concentration & enzyme activity:

11. Understanding: enzymes can be denatured.
Denaturation = permanently changing shape of active site so that substrates can no longer bind or rxn does not occur
Can cause dissolved enzymes to come out of solution and form a precipitate
Caused by 2 conditions:
1) heat
2) Extreme pH (away from the optimum)

12. On individual whiteboards: Draw the graphs for the effects of temp, pH, and substrate concentration on enzyme activity!

14. Nature of Science: Experimental design: accurate quantitative measurements in enzyme experiments require replicates to ensure reliability
Basics to remember when designing your own experiment (IA):
Measure quantitative and qualitative data
Record accurate measurements using accurate units & uncertainties
Provide for repeats, then compare the repeats to assess reliability of data
5X5 Experimental Design is BEST!! (5 forms of independent variable with 5
repeats of an experiment)

15. Understanding: immobilized enzymes are widely used in industry
Remember the falsification of the vitalism theory?
Artificial synthesis of urea in a lab, instead of kidneys synthesizing it (1828, Wohler)
Now we have more support: conversion of sugar to alcohol using only yeast extract without any cells (1897, Buchner bros)
Create immobilized enzymes 3 ways: (Immobilized = can’t move)
Attach enzymes to glass surface
Trap enzymes in gel
Bond enzymes together (aggregates)
Advantages of immobilizing enzymes for the industries that use them:
Easy separation of enzyme and products at ideal time
Easy reusing of enzyme
Increases stability of enzyme to temp and pH changes
Faster rxn rates, since substrates can be exposed to higher enzyme concentrations

16. WHY are all of these advantages for companies?

17. What kind of industries use immobilized enzymes?
Biotechnology
Food & nutrition
Medical
Biosensors (pregnancy tests; blood sugar tests)
Environmental
Agriculture
Energy

18. Application: methods of production of lactose-free milk and its advantages
Lactose = sugar in milk
Lactose = disaccharide: _________ + _________ ?
Enzyme that breaks down lactose = ___________ ?
Lactase obtained from K lactis, yeast in milk
Reasons lactase used by food manufacturers:
For lactose-intolerant ppl (they lack enzyme to break lactose down)
If product needs to be sweet (milk shake, fruit yogurt), glucose and galactose are sweeter than lactose, so less sugar added
Smoother texture for ice cream if use glucose and galactose
Faster production of yogurt and cottage cheese if use glucose and galactose

19. Lactase Products