U1 LE6: For Further Study
Metabolic Managers
Enzymes
1. Enzymes are proteins

They are built by organisms from the
nutrients or biomolecules they take in

Enzymes frequently end with the suffix
“-ase”
amylase, lactase, cellulase, sucrase
Each lock requires it’s own key
Every chemical reaction has it’s
own enzyme
2. Every chemical reaction
requires its own enzyme
Amylase - breaks down starch
 Sucrase – breaks down sucrose
 Lactase – breaks down lactose
 Lipase – breaks down fats
 Polymerase – Builds nucleic acids
(DNA or RNA) from nucleotides
 Helicase – Unwinds the DNA strand

Is this enzyme performing
catabolism or anabolism?
Is this enzyme performing
catabolism or anabolism?
Enzyme
Reactant + Reactant -----------> Product
3. Enzymes have specific shapes
Enzymes can fold into
different shapes based on
the number of amino acids,
the type of amino acids,
the sequence of amino acids.
Ex. Analogy
 26 letters of the alphabet
 Form different words


20 amino acids
Form different proteins
Ex. Ship vs. shipmate – different number and type
Ex. Ship vs. Hips – different sequence
Enzymes have specific
shapes

Lactase is an
enzyme that breaks
down the
disaccharide lactose
into glucose and
galactose
 Only the molecule of
lactose will fit into
this enzyme
 Catabolic or
Anabolic reaction?

chemicalconnection.org.uk
Enzymes shapes can be very
complex . . this is a diagram of
lactase folded
www.10jahresib.ethz.ch/.../educational.html
4. Enzymes catalyze or
increase the rate of reactions

Enzymes speed up reactions by a million
times
 It would take 50 years to digest one meal
without enzymes
 Life
could not exist without
enzymes, because metabolism
would come to a screeching halt
5. Enzymes speed up reactions
by decreasing the amount of
energy needed

Enzymes speed
up reactions by
decreasing the
amount of
energy needed
to start the
reaction

student.ccbcmd.edu
6. Enzymes are not used up
or changed in a reaction
7A. Enzyme Destruction:
Temperature can change it’s
shape or denature the enzyme
High temperatures



Destroy the shape of enzymes –
they can’t do their job
Metabolic process cannot occur
This is why heat stroke can kill
you
http://www.a2gov.org/government/safetyservices/emergencymanagement/PublishingImages/Heat%20Exhaustion%202.gif
Effect of Temperature
on Enzyme Reaction Rate
C
F
30
86
40
104
50
122
The rate of enzyme catalyzed reactions will increase with
increasing temperature (due to an increase of molecule
collisions) until an optimum temperature is reached.
Above the optimum temperature the enzyme changes
shape and is denatured (destroyed).
7B. Enzyme Destruction:
pH can change it’s shape
or denature the enzyme

An improper pH can
destroy enzymes
 Enzymes that work
in specific parts of
the body, need to
work at a specific
pH
Blood pH 7 – 7.45
 Stomach pH 1-4
 Intestine pH 8
 Mouth pH 6.7-7

Effect of pH on
Enzyme Reaction Rate
Pepsin is an enzyme in the stomach and as a pH
optimum of about 1.5. Salivary amylase and alakaline
phosphatase have pH optima of 6 and 9 respectively.
http://staff.jccc.net/PDECELL/chemistry/phscale.gif
7C. Enzyme Destruction:
Salinity can also
denature enzymes
Meet Milo, Larry, Ernest & the Rest
Enzyme Review…
1. Biomolecule Group: Proteins
2. Every reaction has its own enzyme
3. Enzymes have specific shapes (based on
amino acids)
4. Catalyze or speed up reactions
5. Increase the rate of reactions by
decreasing the amount of energy needed
6. Enzymes can be reused for more
reactions
7. High temperatures, salinity, or pH can
destroy or denature (change its shape)