WHAT ARE ENZYMES?
ENZYMES
• a type of protein
– MADE UP OF WHAT?
• Act as Biological Catalysts
–Catalysts: molecules that are
used to speed up a chemical
reaction without actually taking
part in the reaction; the enzyme
remains unchanged
ENZYMES
• Are assembled by our cells
• Are needed for all chemical
reactions including Dehydration
synthesis and hydrolysis
• Provide the right “setting” for
the chemical reaction
– ENZYME ACTIVITY DEMO
By making it easier for substrates to
react, enzymes lower the Activation
energy of the chemical reaction
Activation energy: The amount of
energy needed to convert reactants
into products
- think of it as the “cost” of the
reaction
- the enzyme is a “coupon”
Progress of the reaction
How do Enzymes work?
CATABOLISM
ANABOLISM
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 Demo
What it really looks like
INDUCED FIT THEORY OF ENZYMES
ACTIVE SITE
All enzymes have an optimal temp.
Above that temp. enzymes will be
inactivated
- Increased heat breaks the bonds
holding the protein in a folded shape
All enzymes have an optimal pH.
pH is?
- 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
ENZYME FUNCTION
OPTIMUM TEMP OF THIS
ENZYME?
ENZYME FUNCTION
WOULD THIS MAKE A GOOD
HUMAN ENZYME?
All enzymes have an optimal pH.
pH is?
- changing the concentration of H+
interferes with the bonds holding the
protein in its folded shape.
ENZYMES WORK BEST AT
CERTAIN pH:
DENATURATION
Caused by high temps and pH changes
How fast an enzyme can increase the
rate of a reaction depends on:
1.Concentration of the enzyme
2.Concentration of the substrate
SATURATION CURVE
- What is it telling us? Why does this
happen?
Coenzyme: organic molecules (vitamins)
Cofactors: inorganic molecules (Zn, Cu)
Both attach to the enzyme and
improve chances that the substrate
will bind.
Inhibiting an enzyme
• Inhibit: shut down or suppress
• Can be caused by outside
molecule – drugs/poisons
• Can be caused by inside molecule
if your body wants to temporarily
shut down a reaction
–Why waste the energy?
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,
INSECTICIDES
Non-competitive Inhibition–
molecule binds to a part of the
enzyme and alters the shape of the
active site; No chemical reaction