Enzymes

What are Enzymes?

• Enzymes are proteins that speed up chemical reactions.

• They cause change, so they are also called catalysts.– Reactions can occur without enzymes, but they may

take a really long time. Enzymes lower the amount of energy needed for the reaction to take place.

– http://www.stolaf.edu/people/giannini/flashanimat/enzymes/prox-orien.swf

Enzyme Labeling

Enzyme Labeling

1.

2.

3.

What can enzymes do?• Some enzymes can break down

substances into smaller parts.

• Other enzymes can build substances that cells need.

There are thousands of enzymes!Why?• Each enzyme is specific for one substrate

(the substance it binds to). • The enzyme and substrate fit together like

a lock and a key.• When the substrate andenzyme bind, the enzymeactually changes its shapea little.

http://www.stolaf.edu/people/giannini/flashanimat/enzymes/enzyme.swf

Enzymes are “green”!

• Once an enzyme has finished with helping one reaction, it’s ready for another.

• Enzymes are reusable.

http://www.biotopics.co.uk/other/anenz.html

Do enzymes always work?

• NO - There are two factors that can denature enzymes, or alter the enzyme’s shape and stop it from doing its job. They are:– Temperature http://

www.biotopics.co.uk/other/andnat.html – pH

http://www.phschool.com/science/biology_place/labbench/lab2/ph.html

(Denatured enzyme)http://www.biotopics.co.uk/other/aninac.html

Has the enzyme been destroyed?• “Denatured” does not mean the enzyme

has been destroyed. It has simply lost its shape.

• Enzymes can be “renatured.” If they are returned to normal conditions, they will regain function.

When do enzymes work best?

• Enzymes work best at an optimal temperature and pH level specific for that enzyme. Not all enzymes function at the same temp. or pH.

Amylase- enzyme in mouth

Pepsin- enzyme in stomach

Arginase- enzyme in intestines

Which ones work at the same pH?

How do you know it’s an enzyme?Class Function

1. Oxidoreductase Catalyse redox reactions

2. TransferasesCatalyse transfer of a molecular

group from one molecule to another

3. HydrolasesCatalyse bond cleavage by the

introduction of water

4. Lysases

Catalyse reactions involving the removal of a group to form a double bond or addition of a group to a double bond

5. IsomerasesCatalyse reactions involving

intramolecular rearrangements

6. Ligases/SynthesasesCatalyse reactions joining

together two molecules

What do all these enzyme names have in common?

More Enzyme Animations

• http://www.teachertube.com/view_video.php?viewkey=1879aed110525c185ff3

• http://www.lew-port.com/10712041113402793/lib/10712041113402793/Animations/Enzyme_activity.html

• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html