ENZYME – BIOLOGICAL
CATALYST (PART II)
Objectives for today
Mode of actions of enzymes
 Naming of enzymes
 Specificity of enzymes

Overview
Biological Molecules
Water and
Living
Organisms
Carbohydrates,
Fats and Proteins
Specificity
Speed up chemical
Enzymes
Lock & Key
hypothesis
Mode of Action
Factors affecting
enzyme reactions
Rxn
Not chemically altered at the end
Of Rxn
Lowering Activation Energy
Temperature
pH
Recap
are biological
catalysts found in both
plants and animals.
Catalysts are….?
Enzymes
Cut the wire
Speed up the
cutting process!
Scissors
After cutting,
still remain as
a scissors! Not
altered!
Enzyme as biological catalyst
Speed up the
chemical reaction!
Like condensation
and hydrolysis
ENZYME
Not chemically
altered at the
end of the
reaction!
3. Lower Activation energy
Normal
Day
Exam!
7:29am
6:20am
Reactants = “ You
in bed in home
clothes”
Products = “ You
in school with
uniform”
3. Lower Activation energy
With
Without
Enzymes
Enzymes!
Products =
“Glucose
molecules”
Reactants = “
Starch + Water”
Demonstration on the breakdown
of starch by enzyme (amylase)
Saliva contain amylase,
an enzyme that breaks
complex
carbohydrates
(starches) into simple
sugar (glucose)
“Now that we know enzymes are
catalysts, and roughly know its
shape, but we still do not know
how the enzymes interact with the
reactants!”
How does an enzyme really works?
Mode of actions in 3D view!
Mode of action
1.
2.
3.
4.
5.
Enzymes reaction depends on the availability
of active sites
Active sites are depression or “pockets” on the
surface of an enzyme molecule into which
substrate molecule can fit.
The substrates binds to the enzyme, forming an
enzyme-substrate complex
Reactions takes place at the active sites to
convert the substrate molecules into product
molecules
The products separates, leaving the enzyme
unaltered and free to combine again with more
substrate molecules.
2D view of enzyme in action
5
Activity time!
Using plasticine to model enzymes mode
of actions!
 Split into 4 groups
 Each group
take your
a set ofown
plasticine
Make

enzyme!
Objectives
Make your own enzymes that fits the
substrates given to you
 Time limit is 5mins
 After making, each group is supposed to
describe the mode of actions of enzymes.

Enzymes are specific
Specificity of enzymes explained by
the Lock and Key hypothesis
One key only fits one lock!
 Inside the lock, it has a specific shape that
only takes in the correct key with the
correct complimentary shape.

Enzymes are specific
◦ Each chemical reaction is catalysed by a
unique enzyme
◦ A substrates fits into an enzyme’s activity site
in a way similar to how a key fits into a lock.
◦ Lock and Key hypothesis
How do we name our enzymes?
How do Canberra name their
classes?
3E1
 All the sec 3 classes start with the
number 3
 Follow by E, N or T
 This allows people to quickly recognize
the classes.
 So, how can we name enzymes so that
people can recognize that the names
given actually belongs to the enzymes and
not something else?

ase
Protein
Substrate Name +
-ase
Name That
Enzyme
ase
Lipid
Carbohydrate
ase
Enzyme Nomenclature and
Classification:





Enzymes are commonly named by adding a suffix
"-ase" to the root name of the substrate molecule
it is acting upon. For example,
Lipase catalyzes the hydrolysis of a lipid
triglyceride into fatty acids and glycerol.
Sucrase catalyzes the hydrolysis of sucrose into
glucose and fructose.
A few enzymes discovered before this naming
system was devised are known by common
names.
Examples are pepsin, trypsin, and chymotrypsin
which catalyzes the hydrolysis of proteins.
Quick facts
Any Questions?
Summary
Enzymes
Mode of action
Characteristics
Specific
Speed up
Chemical Rxn
Lower
activation
energy
Lock and key
hypothesis
Remains
unaltered
Induced fit
hypothesis
Requires in
minute amount
Video on enzymes
HW- Due Next Tue 31st March
Go to the biology blog
canberra3E1.wordpress.com and do a short
online quiz. Participation marks will be given.
 Watch a video posted on the web and
 State some common uses of enzymes in our
society
 Scientist can create ‘super enzymes’ that can
break down bio molecules very fast and
efficient. Do you think it is safe to mass
produce this and use it in our society?

Review questions

1) Are Enzymes:
A - Carbohydrates
B - Protiens
C - Nucleic Acids
D - Lipids
E - Other
Going a bit further
G6PD, a functional enzyme gone missing
in in the body!
 Cannot break down Glucoe-6-Phosphate,
which will be accumulated in the cells.
 And it disrupts many other chemical
reaction in the body

G6PD enzyme
Next lesson

Factors affecting enzymatic reactions