Download Enzymes

Control METABOLISM
Metabolic reactions can be
controlled and sped up by
enzymes
• metabolic reactions would be too slow
to occur if no enzymes were present!
• End in “ase”
Properties of Enzymes
1. Proteins
2. Catalysts
3. Reusable
Properties of Enzymes
4. Substrate
specific
5. Sensitive to
temperature
6. Sensitive to pH
Enzymes Remain Unchanged!
Enzymes are not
used up; Reaction
ends when there is
NO MORE
SUBSTRATE!!
Before
After
Mechanism of Enzyme Action
• THE ACTIVE SITE is the place where
the substrate binds with the enzyme
substrate substrate
active site
enzyme
Action of Enzyme in
Synthesis (TO MAKE)
substrate
enzymesubstrate
complex
Product
and
substrate
enzyme
Action of Enzyme in
Decomposition (TO BREAK DOWN)
enzymesubstrate
complex
product
substrate
enzyme
Lock and Key
Hypothesis
Enzyme
Substrate
Lock and Key
Hypothesis
Lock & Key Model
ONE enzyme
for every substrate
Unique fit
Enzyme
Substrate
Enzymes are Temperature
Dependent…...
Most work BEST at body temperature
37oC
DENATURE (change shape) at high
temperatures
Inactive (doesn’t work that well) at
LOW temperature
What is the optimum temperature for
this enzyme?
How do you know?
What is pH?
Used to determine the acidity or alkalinity
(base) of a solution on a scale on which 7
is neutral, lower values are more acid, and
higher values more alkaline (basic)
Effect of pH on Enzyme
Activity
-If pH of the substrate is higher or lower than
optimum pH (highest enzyme activity)
denaturation happens; enzyme becomes
ineffective.
-Different enzymes may have different
optimum pH’s
What pH does pepsin work best?
What pH does pancreatic lipase work?