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/enz
ymes/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 and
enzyme bind, the enzyme
actually changes its shape
a 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/labbe
nch/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. Transferases
Catalyse transfer of a molecular
group from one molecule to
another
3. Hydrolases
Catalyse 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. Isomerases
Catalyse reactions involving
intramolecular rearrangements
6. Ligases/Synthesases
Catalyse reactions joining
together two molecules
What do all these enzyme names have in common?
More Enzyme Animations
• http://www.teachertube.com/view_video.php?vie
wkey=1879aed110525c185ff3
• http://www.lewport.com/10712041113402793/lib/107120411134
02793/Animations/Enzyme_activity.html
• http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapte
r2/animation__how_enzymes_work.html