You’re eating a carrot…
1. you begin to chew (manual breakdown)
 2. you are salivating as you chew

 Amylase
in salvia
 Amylase is a digestive enzyme classified as a
saccharidase (an enzyme that breaks down polysaccharides).

3. Amylase is an ENZYME

What is an enzyme?
 GOOD
QUESTION!
Enzymes
Function of Enzymes

Enzymes speed up the rate of reactions
 Enzymes


can be called catalysts
Not all catalysts can be called enzymes
They do NOT
 Change
the reaction
Enzymes

Most enzymes are proteins.
 ribozymes

Not all proteins are enzymes.
Enzymes and Substrates

Enzymes affect substrates
 Substrate-

substance on which an enzyme acts
specific enzymes can only fit with specific
substrates called
SPECIFICITY
 lock and key model
All pictures demonstrate the same
thing. A perfect fit between enzyme
shape and substrate shape.
Active Site

Active sites are where the enzyme and
substrate will meet when they create the
enzyme-substrate complex.
Enzymes

Shape determines function
 enzymes

are very specific in their function
Under normal conditions, enzymes do not
change shape even after they perform their
function.
This means that enzymes can be used
over and over again.
Enzymes speed up reactions
that would happen normally…
Enzymes

Enzymes are biological catalysts.
 enzymes
things

speed up the rate of reactions in living
Chemical Reaction:

Reactants and products
Protease; what is the function of protease?
Reaction with an enzyme
Enzymes bind temporarily to the reactant
 In doing so, they lower the amount of
activation energy needed to start the reaction.
 Therefore, reaction time is increased.

Enzymes

Activation energy refers to the amount of energy
a system needs to initiate a process.
Enzymes
Enzymes

factors can affect the shape of an enzyme:
temperature
 pH
 Alcohol
 Heavy metals
 Reducing agents

 Denature
Enzymes: OPTIMAL RANGE
Enzymes works best when in their proper
environment
 activity decreases at values above and below its
optimal range.
 Ex.

Induced fit
Enzyme is partially flexible
 Substrate can somewhat modify the active
site to fit

 Explains
why some substrates bind but do not
react with enzyme; too much distortion during
induced fit
Competitive inhibitor
Allosteric regulation
Exit Card 

1. Look at the picture. Name parts: A, B,
C, D and E