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Presentation on theme: "Enzymes."— Presentation transcript:

1 Enzymes

2 What are enzymes? Enzymes are proteins (tertiary and quaternary structures) that catalyze (act as catalysts) the rate of a chemical reaction (increase). They do this by decreasing the amount of activation energy required for a reaction. Not permanently changed in the process

3 Enzymes Are specific for what they will catalyze Are Reusable
End in –ase -Sucrase -Lactase -Maltase

4 Enzymes are very specific...
For example, the lipase substrate (lipids) would not attach to amylase.

5 How do they work? Activation energy is energy that chemicals need in order to begin a reaction Example: Frogs leaping over a pile of rocks. The higher the barrier (activation energy) the less frogs can get over (or less product is created).

6 How do enzymes Work? Enzymes work by weakening bonds which lowers activation energy

7 Enzymes Without Enzyme With Enzyme Free Energy
Progress of the reaction Reactants Products Free energy of activation

8 H2O2 is a breakdown product of aerobic respiration
H2O2 is a breakdown product of aerobic respiration. Catalase breaks down H2O2. Catalase is in peroxisomes (in cells) and rid the body of toxins. Peroxisomes are concentrated in the liver and the kidneys.

9 Enzyme-Substrate Complex
An enzyme acts on the substrate (chemical substance) Enzyme Joins Substrate

10 Active Site A region of an enzyme molecule which binds to the substrate. Enzyme Active Site Substrate

11 Enzyme-Substrate Complex: Lock and Key Theory
-The substrate attaches to the enzyme’s active site. -Enzymes and substrates fit like a lock and key.

12 Life cannot exist without enzymes!
Without enzymes, every day reactions would be far too slow for us to survive. Unable to break down toxic wastes in a timely manner. Unable to metabolize our food fast enough. Life cannot exist without enzymes!

13 Induced Fit Theory the enzyme changes its shape slightly to create a more secure bond with substrate, and then the chemical reaction follows.

14 Induced Fit A change in the shape of an enzyme’s active site
Induced by the substrate

15 After the chemical reaction, the product is released from the enzyme
After the chemical reaction, the product is released from the enzyme. The enzyme is free to carry on the same chemical reaction again and again (enzymes can be reused).

16 What Affects Enzyme Activity?
Four factors: 1. Environmental Conditions 2. Cofactors 3. Coenzymes 4. Enzyme Inhibitors

17 1. Environmental Conditions
A. Extreme Temperatures are the most dangerous - high temps may denature (unfold) the enzyme. B. pH (most like pH near neutral) C. Ionic concentration (salt ions)

18 Factors that Affect Enzymes
-Two factors that affect enzyme productivity are pH and temperature. -Enzymes thrive best within certain temperature and pH ranges, and cease functioning in others. Example: people die of fevers not because of the high temperatures, but because the enzymes in their body do not function properly once the temperature gets too high.

19 Examples of Enzymes Enzyme Substrate (the Reactant) Location in Body
Amylase Carbohydrates / sugar Mouth Lipase Fats Various locations Pepsin Proteins Stomach Trypsin Small intestine Lactase Dairy

20 2. Cofactors and 3.Coenzymes
Inorganic substances (zinc,magnesium,copper,iron) and organic vitamins (respectively) are sometimes need for proper enzymatic activity. Example 1: Iron must be present in the quaternary structure - hemoglobin in order for it to pick up oxygen. zinc must be present to break down alcohol (alcohol dehydrogenase) Example 2: The coenzymes make up a part of the active site, since without the coenzyme, the enzyme will not function. vitamin B-12 - vitamin coenzyme B-12 - coenzyme Methyl group transfer - function

21 Two examples of Enzyme Inhibitors
Many drugs are enzyme inhibitors as well as chemicals such as herbicides and pesticides and neurotoxins. a. Competitive inhibitors: are chemicals that resemble an enzyme’s normal substrate and compete with it for the active site. Enzyme Substrate Competitive inhibitor

22 Inhibitors b. Noncompetitive inhibitors:
Inhibitors that do not enter the active site, but bind to another part of the enzyme causing the enzyme to change its shape, which in turn alters the active site. The most common uses for enzyme inhibitors are as drugs to treat disease, an example is drugs used in chemotherapy, viagra, and anti-epilepsy medication. Enzyme Noncompetitive Inhibitor Substrate active site altered

23 Enzymes play a critical role in everyday life.
Many heritable genetic disorders (diabetes, Tay-Sachs disease) occur because there is a deficiency or total absence of one or more enzymes. Other disease conditions (cancer) result because there is an excessive activity of one or more enzymes. Routine medical tests monitor the activity of enzymes in the blood, and many of the prescription drugs (penicillin) exert their effects through interactions with enzymes.

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