ENZYMES
ENZYMES
A
type of Protein
MADE
UP OF WHAT?
A folded chain of amino acids
In

living things they act as
Catalysts
molecules that are used to speed up
a chemical reaction without being
changed in the reaction; the enzyme
can be used over and over again
LABEL THE PARTS
Substrate
(Reactant)
Products
Active Site
Enzyme is unchanged
WHEN WE EAT ENZYMES….
We can’t use them…what has
to happen first?

ENZYMES
Break
down enzymes (like any
protein) in the digestive
system.
Our enzymes are made by
assembling these amino acids
to form “human” proteins
Enzyme Activity Demo
ENZYMES
Are
needed for all chemical
reactions including
Dehydration synthesis and
 Hydrolysis

Provide
the right “setting” for
the chemical reaction
HOW DO ENZYMES WORK?
Orient the substrate molecules
correctly

Increase
the likelihood a
reaction will occur!
Enzyme
Demo
ACTIVATION ENERGY
Enzymes
make it easier for
substrates to react

This is how the activation energy is
lowered
Activation

energy
The amount of energy needed to
convert reactants into products
This is the “cost of the reaction”
The enzyme is a “coupon”
ENERGY PLOT
Progress of the reaction
CHEMICAL REACTIONS
Some
chemical reactions
release energy
What has more energy, product or
reactants?
 What type of reaction is this?

Some
input

reactions require energy
Answer the two questions above
again!
HOW DO ENZYMES WORK?
CATABOLISM
ANABOLISM
THE CATALYTIC CYCLE OF AN ENZYME
Breakdown of Sucrose to Glucose and Fructose
Using Sucrase
BUILDING REACTIONS USE….
Breakdown reactions ………
Using different words for the
same event…..
SPECIFICITY OF ENZYMES
 Enzymes
are EXTREMELY specific
 There
is a unique enzyme for
EVERY substrate that reacts in the
body
 Each
enzyme’s active site will ONLY
fit one specific substrate
LOCK AND KEY MODEL
LOCK AND KEY (ACTUAL SHAPE)
INDUCED FIT THEORY -ENZYMES
ACTIVE SITE
part of an enzyme
where substrates
bind and undergo a
chemical reaction
If this location is
changed (damaged,
mutated, etc. , the
reaction cannot
take place.
WHAT IMPACTS ENZYMES

Temperature
All enzymes have an optimal
temperature.
 Exceeding optimal may cause enzyme
inactivation (denaturation) due to
breakage of bonds in quaternary and
tertiary structures.

WHAT IMPACTS ENZYMES
pH
 changing
the concentration of H+
interferes with the bonds holding
the protein in its folded shape.
 Raising
or lowering pH above or
below optimal will cause
denaturation.
OPTIMAL PH
pH
is?
changing
the concentration of
H+ interferes with the bonds
holding the protein in its folded
shape.
ENZYMES HAVE SPECIFIC PH
DENATURATION
Caused by high temperatures and pH changes
HOW FAST AN ENZYME WORKS ALSO
DEPENDS ON:

Concentration of the Enzyme
Concentration of the
Substrate (what it is putting
together or taking apart).

SATURATION CURVE
What does this tell us? Why does this happen ?
COENZYMES AND COFACTORS
Coenzymes

Organic molecules such as vitamins
Cofactors

Inorganic molecules or ions such as Zn and Cu
Both attach to enzymes and improve
chances that substrate will bind to the
enzyme.

Cofactor animation
ENZYME INHIBITION
 Inhibit:
shut down or suppress
 Can
be caused by outside molecule –
drugs/poisons (poisons, drugs
 Can be caused by inside molecule if
your body wants to temporarily shut
down a reaction

Why waste the energy?
EXAMPLES – EXTERNAL
 Cyanide
inhibits one of the
enzymes in cellular respiration
(oxidase)


RESULT: less oxygen  less ATP  death
Penicillan works by inhibiting a
bacterial enzyme involved in
making the cell wall. The bacteria
is unable to reproduce.
Nerve
gas interferes with
acetylcholinesterase
RESULT:
acetylcholine cannot
be hydrolyzed nerve signals
cannot be passed from nerve
cell to nerve cell.
EXAMPLE - INTERNAL
Feedback inhibition in a
biochemical pathways

Feedback inhibition is a form of
inhibition
COMPETITIVE INHIBITION
molecules
that are similar in shape
to the substrate bind to the active
site and block the substrate; No
chemical reaction can happen
Examples:
Drugs and Insecticides
ANIMATION INHIBITION
NON-COMPETITIVE INHIBITION
molecule
binds to a part of the
enzyme and alters the shape of the
active site; No chemical reaction
INTERPRETING ENZYME GRAPHS
 What
is the optimum temperature
for this enzyme?
INTERPRETING ENZYME GRAPHS
 Would
this make a good human enzyme?